Surprise! The well known GMC grilles from 1949 through early 1955 use the same bars. This includes the more popular ½ ton through the very large over the road and quarry trucks. Chrome or painted, the four horizontal stamped metal bars are identical. Look at the following photos. The grille bars interchange!
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In the days when car and truck owners as well as mechanics did maintenance, GM made these responsibilities much less complicated. An excellent example was the screen below the engine oil pump.
Due to no oil filters and no detergent additive in the motor oil (to keep dirt in suspension), the oil pump screen was necessary. Tiny dirt particles settled to the bottom of the oil pan as was expected. The small dirt particles finally became dirt chunks stuck to the bottom of the oil pan.
GM wanted no chance that a chunk or clot of dirt might be drawn to the pump. Thus, oil pulled into the pump had to pass through this screen.
These photos show several early screens used by various Chevrolet six cylinder engines. Note the used screen on the 1937-53 216 engine. Its rounded screen is held in place by a single wire. The wire can easily be unhooked from the housing. The screen then drops out for easy cleaning.
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| 1937-53 wire holding screen | 1937-53 wire unhooked to remove screen |
An Inner-Line oil filter from Long Island, New York! Rarely seen today but a popular early aftermarket option. It secures to the engine block after removing the oil distribution cover. No oil lines. No moving the horn forward to make room for the intake manifold mounted oil canister.
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When your older truck needs a rebuilt speedometer, think of us! Our company, in combination with a local specialized shop, provides a quality product that you will be proud to place in your vehicle.
With most new repair parts, no longer available, we obtain used speedometers from across the country. Only the best parts are removed. These are combined with available new components to create a quality finished product. The following photos show various stages in the repair process.
It is very unusual that we are asked to create a 1954-55 GMC gauge panel. Our customer had lost his due to an un-professional rebuilder and was in a panic. We finally were able to create this set after an involved hunt in our various storage locations. What a job! All needed complete rebuilding and appearance upgrading.
We thought this should be on our Tech page to show their original new appearance. After all, we may never find parts to rebuild another.
What a unique invention. When you have a 1947 through 1959 single rear wheel 3/4 or 1 ton GM truck and need more pulling power, this is the answer. American ingenuity at its best!
This new steel center hub extension includes eight long bolts to reach the original wheel studs. This holds the factory wheel in place and then provides a threaded end for the original eight lug nuts which are holding another matching wheel.
The buyer of this aftermarket kit just had to be sure his new outer tire was the same height as the original inner tire.
Pictures and data from Scott Golding, Stratton, NE.
email: scottandbetty@hotmail.com
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It is very important where to drill the hole for the new radio antenna. The results of making a slight mistake will stay in your mind for many years to come!
Radios during these 1947-54 Advance Design years were never installed at the factory. This was done by the authorized GM Dealer. In the box that contained the new radio was a paper template that prevented mistakes when drilling the antenna hole. This hole in the cowl was so close to the belt line that the body to the antenna seal gasket even lacked an edge where it touched this body belt. Even with GM moving the antenna so close to the belt line there is still only about 1/2″ clearance to the hood when it is open. See photo.
The sad realization occurs later when a new radio antenna is installed by an amateur. He drills the hole in the cowl (correctly on the driver’s side) about another 3/4′ forward. He smiles as the radio works great. He doesn’t smile a week later when he tries to raise the hood to check the oil. It won’t raise! The rear hood edge hits the antenna. A rubber plug later put in the new hole is always a reminder of what a 1/2′ can do.
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| Hood Closed | Hood Open | Hood Open |
Over the many years we have collected a wealth of knowledge working with Chevrolet and GMC trucks from the years 1934 – 1972. We have gathered our Tech Articles, write-ups and how to’s and divided them into categories. You will find a list of helpful Articles that will help you get your old truck looking and running like new again.
One of the most unique GM body styles is the famous COE (Cab Over Engine) design. By placing the cab over the engine of a large truck the wheel base could be shorter. This allowed the same maximum payload to be carried in a shorter truck.
These became quite popular in crowded downtown deliveries. The COE truck could turn in a shorter radius, on tight corners, iin narrow alleys, and still carry the same payload.
Disadvantages:
Click images to enlarge
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| 1946 Chevrolet COE | Owned by: Jim Cadorette 1946 with 2000 6.5 turbo diesel with 4 speed Over Drive | ||
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1951 COE | 1940 COE | 1940 GMC COE | 1947-1955 Fender Pad |
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| Owner: Koos Diedel from the Netherlands…1950 Red, 3 years to make it more “Freeway” friendly. Buick V-8, Air ride & so much more…”1951 Black – Bone Stock” | 1939-1946 COE grab handles (to pull yourself up into the cab) | 1939-1946 The left 2-leg mirror arm attached to the door. |
1941-1946 Close Up – COE Grill |
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| 1947 – 1950 GMC COE 9 foot 1 ton 1947- 1953 pick up bed on a modern chassis. |
1947 – 1953 COE | 1941-1946 COE Steps, To get into the Cab… | |
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1941 COE
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1949 COE
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1939 COE
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1940 Chevrolet COE
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Looks Expensive
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The Restoration Begins 1950 COE
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COE Cover of 2009
Convention Program |
Coming Soon
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Coming Soon
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Owner Unkown
If you would like your Chevrolet or GMC Cab Over Engine featured on our website, please send us an email along with your name, year, make, and model of your truck along with your photos. You can email your information by using our contact email form…click here
One of the most unique GM body styles is the famous COE (Cab Over Engine) design. By placing the cab over the engine of a large truck the wheel base could be shorter. This allowed the same maximum payload to be carried in a shorter truck.
These became quite popular in crowded downtown deliveries. The COE truck could turn in a shorter radius, on tight corners, iin narrow alleys, and still carry the same payload.
Disadvantages:
Go To – Page 2 COE Trucks
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1946 Chevrolet COE, Billy Marlow (all above) Read Billy’s Story..click here
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| 1948 Owner Ken Wedelaar, Midland Park, NJ |
1954 Owner George Coe
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1951 …Owner Jim Carter, Independence, MO | |
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1940 Owner, Unkown
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I found this 1946 COE in Fall City, WA and it is now in Soldotna, Alaska. I shipped the truck From Tacoma Wa to Anchorage Alaska on Totem Ocean Trailer Express (TOTE). I have driven it about 500 miles since I bought it. Jim Fassler Soldotna, Alaska |
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COE Salvage Yard
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1941 – 1946 for Parts
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1946 for Parts
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1940 Unknown Owner
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Three clear seal beams on a 1946! What could have been the purpose?
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1941-1946 GMC owner unkown
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1938 GMC COE… |
1954 Chevy COE
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Owner Unkown
If you would like your Chevrolet or GMC Cab Over Engine featured on our website, please send us an email along with your name, year, make, and model of your truck along with your photos. You can email your information by using our contact email form…click here
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Another fine example of an old
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The issue of multiple piece rims and safety comes up frequently. There seems to be a quick rush to judgment about any rim that has more than one piece, and while certain types of multiple piece rims have indeed been outlawed and are no longer made, many others are not only still in service, they are still made new.
1947-1954 light duty trucks offered split rims in 1/2 ton (optional only) up to 1 ton trucks. Many people are unaware that there was a 1/2 ton two piece 15″ six lug rim option available in GMCs and I presume Chevy too. More often than not, we run into eight lug two and three piece rims on 3/4 ton and one ton trucks and these are the subject of most of the misinformation.
There were two types of split rims offered originally a 3/4 ton GMC; 15″ TWO piece split rims (Kelsey-Hayes type WK-3), and optional 17″ THREE piece split rims (Kelsey-Hayes type WK-4)
The two piece split rim uses a lock ring that is fixed and is one solid piece. There’s a notch in the rim where you can remove and reinstall the bead retainer ring while mounting and breaking down tires. To remove, you tip the ring at an angle and then slip it by the notch. To mount, do the opposite. This type DOES NOT require prying apart the ring and if you try to pry it off, you’ll ruin ix
The 17″ split rims originally would have been the Kelsey-Hayes type WK-4 and are three pieces; the rim, the bead ring, and the lock ring. They are put together pretty much the same way they do now-a-days on big truck rims. The tire goes on the rim, then the ring slips on and then the third ring is “zipped” on/off using a sledge hammer and pry bar.
The safety of these rims is directly dependent upon their overall condition. I have split rims on all three of my vintage GMCs. You will find knowledgeable truck tire places will work on them without hesitation and car tire places will go screaming in circles with their hair on fire spewing misinformation about “suicide” rims which may or may not be applicable, but does more to spook people than inform them with facts.
I have many many miles on my original split rims and find them to be great for my purposes. Others may have different views of what works for them. See the illustration below to understand the three basic types of original stock rims you’ll find on the old GMC trucks.
View PDF Chart of 1947-1954 Split Rims Click Here
Beginning in 1951 these bumpers became an extra cost option and have remained this way ever since on most pickup models.
The reason relates to trucks being mostly for work. Though protecting the bed from minor rear damage, a bumper also kept the driver from backing up against a loading dock. GM found that many farmers and construction workers had been removing the rear bumper to get the truck flush against a dock. This eliminated most of the gap between the truck and dock. Broken legs of livestock and employees during loading were also greatly reduced.
The following picture is an example of a 1955 and newer GM step bed pickup. Its owner went against the current trend of adding the optional rear bumper during its restoration and kept his truck basic. It is important to note, that to protect the license plate bracket without a bumper, GM placed it on the left side. Holes are in the middle of the rear cross sill from the factory to make it easier for the dealer to install the rear center license plate bracket while adding the optional bumper.
Note the rear spare tire arm is at an angle to also protect it from damage if backing or being hit.
This picture shows an optional right taillight. From the assembly line this truck would have only the left light with attached license bracket.
Without optional bumper. Owner has added a right tail light. (above)
Factory installed optional bumper including correct tail lights and license bracket (above)
Purchasing a 1947-1953 optional cigarette lighter assembly from some vendors provides reproduction that is far from original in appearance. A manufacturer recently offered the optional lighter assembly but used a knob from the headlight of a 1947-1953. There is no similarity to the real lighter!
Reproduction (above)
Image of original (above)
Prices of more valuable metals such as copper and nickel reached their height during mid 1951 through 1953. Though U.S. shortages were much less than in WWII, there were price increases in the market that affected the financial bottom line of auto and truck manufacturers.
America almost demanded chrome on cars even if it raised prices. Decorative shiny trim was almost necessary to get buyers into the showroom.
Trucks were a different story! They were work vehicles. Eliminating the chrome extras did nothing to lessen the load capacity or operations off road. To keep the price down GM and other truck manufacturers removed much of the chrome and replaced it with paint. The steel stampings were the same, they were just painted. It was very necessary for GM’s base model to be priced low. City, county, federal, and many companies bought fleet trucks that offered the lowest price. Purchases had little to do with appearance. Even a $10.00 savings could make a sale.
The noticeable changes on GM light trucks is the lack of chrome on hub caps, grill bars, bumpers, and even the wiper knob. Stainless steel also felt the Korean War shortages. The deluxe five window pickup cab no longer had the stainless around the windshield and side windows. The glove box as well as the radio speaker horizontal trim was now painted steel. The deluxe panel truck with all its extra stainless side trim was now history.
By 1954 the chrome and stainless was back stronger than ever though some base models were kept in paint to hold their price low.
The following photos show just a few examples of GM’s Korean War era trucks. Considering their uses it doesn’t look too bad.
The 1955 year put Chevrolet on top! All stops were removed in announcing and continual advertising of the totally redesigned passenger car and their first V-8 engine. Television, radio, news papers and dealers regularly told the public that Chevrolets best year had arrived.
It was not good timing to also begin an equal advertising campaign for the totally new truck that was ready for manufacturing. A good business decision by GM was to wait about six months until the car ads had slowed, then advertising could begin again for their redesigned trucks. This would hit the customers twice in one year on major changes in the Chevrolet market.
It was unheard of for GM to not introduce a new Chevy vehicle each year, therefore at least something had to happen with trucks at the beginning of the 1955 model year. The answer was later called a “First Series 1955″. Chevrolet would introduce the 1955 truck by making several changes to their pre-existing 1954. With the new “Second Series” only months away, little investment was made to the early 1955 trucks.
The most noticeable change on the popular 1/2 ton was the first open drive shaft in Chevy’s truck history. This was actually created for the later 1955 trucks but with dealer demand it was moved up to be in the early body style. This major drive line change required a different 3 speed transmission, rear leaf springs, shift linkage and shift box.
The outside visual changes were minimum. During the about 5 months production, the 1955 early truck was given totally different hood side emblems. However, to reduce costs the number portion of the emblem could be changed depending on the size of trucks. Example: 3100 on 1/2 ton, 3600 on 3/4 ton and 3800 on the 1 ton.
A no cost difference was changing the vertical stripes on the front hood emblem from red on the 1954 to white on the 1955
The paint arrangement on the non-chrome grill was also a non cost change for Chevrolet. The grill bars were changed from body color to white.
Interior paint (again a no cost change) was slightly modified from a pearl beige color 1954 to a light metallic brown.
Thus, with little extra investment Chevrolet had a new truck for the beginning of 1955. This was the final offering of this body style that began in 1947. GM referred to it as the “Advance Design”. It has become one of Chevrolet’s all time greats. It’s popularity today is as strong with hobbyists as it was with new buyers 50 years ago.
Then came the totally re-designed trucks in mid-year 1955. That will be another story!
As per GM, accessories during the 1930′s through mid 1960′s were the extra cost items sold and installed by the approved dealer. The truck was prepared for these during production so the dealership could later add them with less effort.
As much as possible GM would punch holes, attach removable plates, press in dimples, etc. to help the dealership in placing the accessory in just the right position. Several accessories using the pre-placed holes or dimples in these early Chevrolet and GMC trucks are the right side taillight bracket, fresh air heater, radio, front bumper guards, cigarette lighter, arm rest, glovebox light, and windshield washer.
Options were added at the factory. They were more difficult to install by individual dealerships and were therefore placed on the vehicle during production. This included items such as a chrome grille, 4 speed transmission on 1/2 and 3/4 ton chassis, double action shocks, tinted windows on 1953-55, two speed rear axle on larger trucks, double action fuel pump, hydrovac power brake, etc.
This was one of the most unique years for General Motors trucks. The Korean War and some resulting material shortages were now history. The economy was growing and the average worker brought home more wages than ever before. Sales of luxury options on automobiles were showing definite increases.
To capitalize on this trend for transportation improvements, GM was fast working on total new automobile and truck models for the coming year. When introduced, the result would be record sales which put General Motors even further above it’s competitors.
But what about the 1954 year for GM trucks? Waiting buyers had the demand for a new updated truck but the tooling was not yet complete. Other competitive truck manufacturers were beginning to offer many deluxe features.
Therefore, General Motor’s 1954 answer to temporarily satisfy new truck buyers was a major facelift of the prior models. To keep costs down, GM continued to use the basic cab introduced in mid-1947. To update this seven year old design, an enterprising engineering department added items such as a one piece curved windshield, completely redesigned dash board, and created a totally different grill. All this while keeping almost identical hood, fenders, bumpers, running boards, seats, doors, etc.
Another big first for 1954 Chevrolet truck cabs was the optional color coordinated interior and the two tone exterior. This had never been offered before by GM on truck cabs. Advertisements defined it as “The Bold New Look”. For an extra cost (only on cabs with rear quarter windows), the customer could order interior color combinations including two tone blue, gray and maroon, two tone green, plus dark and light brown. Each of these four base color combinations were harmonized with the headliner, floor mat, door panels, windlace, and interior sheet metal. Pearl beige was the standard color on non optioned cabs.
This deluxe two tone interior package was introduced in mid year. Therefore, it is not shown in early 1954 Chevrolet truck brochures and many perfectionists do not know it was available later.
The two tone exterior paint option included a white top only (shell white) and only on the deluxe cab. For the short run in 1955 of this body design (first series), the two tone was still with only a white top but the shade was changed to Bombay Ivory.
With fears of Korean War shortages now over, chrome and stainless steel could now be offered again as part of a long option list. On the deluxe model this included stainless exterior window trim plus chrome hub caps, grill and bumpers.
The option list also increased greatly for the 1954 year with new items available not offered during previous years. Examples were full wheel covers, electric wiper motor, automatic 4 speed transmission, ride control seat, day-night inside rear view mirror, etc.
It is also important to remember that for 1954, Chevrolet chose to introduce two major items and not wait for the totally new later 1955 models. This was the high pressure insert bearing six cylinder engines and the deeper restructured pickup bed. Thus, the 1954 shares both the early and late features and is a true “transition truck”.
At present, the 1954 GM light pickups, particularly the deluxe models are showing a fast increase in popularity among restorers. They stand out as a unique transition truck having various characteristics not associated in total with any GM commercial vehicle. It is felt their future pricing will also stay higher than either 1947 to 1953 or the 1955 to 1959 models in equal condition. Of course, all older GM trucks are on their way to the top in popularity and value. They are to restorers “the Model A’s of a New Generation”.
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On the original rear end, the spring centerbolt is offset to the front of the spring by 2″to 3″. If you install a modern rear end (with an open driveshaft) and retain the original springs, the wheels will end up offset forward (inside) of the original wheel openings in the fenders. To correct this problem, remove the original springs and reverse them end to end (front to back) as they are the same on both ends. This will bring the spring centerbolt to the rear of the axle and place the new rear end in the center of the fender wheel openings.
Click to enlarge
GM trucks titled prior to the mid-1950′s were usually registered using the stamped engine number not the body digits pressed in the door ID plate. This practice has created many problems in later years as states became stricter in titling.
Unfortunately, many older vehicles outlast their engine and owners rarely rebuild the originals. To save time and certainly expense, a rebuilt unit or a used one from another vehicle would often be installed. This worked great until years later when state safety inspections began or the vehicle was sold out of state. With a prior engine transplant, there was no ID numbers that would match the title.
Even today, this problem occurs as older trucks with different engines are pulled out of barns and from the property line of a farmer’s back field.
On 1937-55 1/2 and 3/4 ton rear bumpers there exists an unused center square bumper bolt hole that sometimes brings up questions from restorers. “Why does this hole exist and what is it purpose?” The answer relates to the attitude toward trucks during those years. They were for work and keeping their production cost low was a priority.
The bumpers during 1937-47 were the same front and rear. The center hole at the front held a vertical steel bracket which was needed if the truck was hand cranked. Rather than make a 4 hole rear bumper, GM simply used their front on the rear. Even in 1947-55 with a slightly different horizontal shape, the factory 5 hole punch was used on front and rear. Therefore, the rear bumper hole has no purpose. To cover this hole, GM produced a special bumper bolt that has become very rare. To save costs (it is a surprise that anything was used) GM created a one inch long stud held in place with a sheet metal speed nut. It has no threads and its head is covered with a stainless cap so it looks like the other bumper bolts from a distance.
Most of these original rare filler bolts will have dents and scrapes on the stainless cap. A skilled person can place a new stainless cover from a more common replacement bolt and make this rare unit look like new.
Of the many differences between the Chevrolet and GMC 1/2 ton during the early years (1936-54), the GMC offering of a long bed pickup box was one of the more noticeable. Only GMC provided this option. To obtain this extra bed length on a Chevrolet, the buyer ordered a 3/4 ton.
This difference existed with the first GMC pickup in 1936 and continued through the end of the Advance Design series in 1955. Possibly the reasoning for this was the horsepower difference between these two marquis. The base 216 six cylinder Chevrolet engine provided 92 hp. The standard 228 GMC six boasted 100 hp.
To get the approximately nine inch extra GMC chassis length not only were the two frame rails longer but the drive shaft was extended. GMC engineers did this by developing an extension which was the connecting length between the standard short bed closed drive shaft and the rear of the transmission. None of this interchanges with a Chevrolet and both makes use a totally different drive shaft design on their 3/4 ton series.
The adjacent photo shows this unique connector link installed in its GMC. A 7 3/8 inch steel jack-shaft is surrounded by a cast iron housing (it is still a closed drive shaft) and includes an extra u-joint, bearing, and seal. Though, a strongly built drive shaft system, this portion becomes the long bed 1/2 ton’s weak link after 50 years of use and abuse. Without a doubt this link has performed almost flawlessly beyond the miles expected by its designers. However, it does have its long term limitations. The many prior miles, lack of regular maintenance, and occasionally overloading the truck makes the failure of an original in today’s world a definite possibility. Watch for sources for the rare replacement parts in this connector link just in case. Otherwise surprise damage in this area can keep your GMC 1/2 ton long bed out of service for quite some time.
When you would like to restore your truck and no workshop is available, there is a solution. Most all the repairs can occur in a temporary shop and at a very low cost.
Jim Valano of Marion, Indiana is a true example of ‘American Ingenuity.’ He purchased a ‘canvas storage tent’ and assembled it at a convenient location. He even made the floor using the backside of used carpet on top of sheet plastic. Its roll-up sides are adjusted for the weather.
Jim’s 1957 Chevrolet ½ ton is now almost restored and most of the work occurred in this canvas enclosure. It can later be removed and stored in the original box.
If you need a building for your restoration, this may be your answer. Just check with your city for possible zoning restrictions!
The body I.D. plate – every GM truck had one attached at the factory. Basically it states the vehicle’s gross weight limit (weight of truck plus its maximum allowed load) plus stamped digits that give the assembly plant year, size of truck, month built, and sequential numbers as it came off the production line. These plates are necessary for positive vehicle identification.
A unique characteristic of the 1950 and older GM truck is that the I.D. plate was not riveted at the factory but rather held in place by two small clutch head screws with a hexagon perimeter. Thus a wrench or a clutch driver can tighten or remove them.
Over the years if the two screws begin to loosen, the owner would either retighten them from time to time or often remove the plate for safe keeping. Usually this plate stayed in the glove box or at home and just never got reattached. Thus we find some of these pre-1951 GM trucks with no I.D. plates. In the early years this was often of little concern as most trucks were titled on the engine number.
After 1950 these I.D. Plates were riveted to the door post. Probably not so much to prevent vehicle theft (we lived in a different era) but just to keep them from being lost.
In today’s world this can cause big problems in registering particularly if the transfer is to another state and an I.D. number verification is necessary. Even if the I.D. plate remains secure with screws as it left the factory, a problem may still exist. Unfortunately most inspectors today weren’t even born when these trucks were built. Sometimes an officer refuses to OK the truck, saying that I.D. plates do not come with attaching screws and it is not legal. You now have an uphill battle with an inspector that really believes he is correct.
Yes, you can attach this original scratched and painted-over I.D. plate with rivets. However, what is this inspector going to say when he sees this worn and painted on I.D. plate attached with two new shinny pop rivets? Have you ever been accused of car theft? It is then you wish the truck was titled to the engine!
Remember, on a left hand drive truck (1947-55) the I.D. plate attached to the left door post. It is attached to the opposite side on the right hand drive truck. The two holes for the plate screws or rivets are punched at the factory in both door posts.
To keep the 1947-1955 GM trucks base price low, their 6 volt cigarette lighter was a dealer accessory. The vehicle always came from the factory with a round blank out plug at the lower center of the dash.
To save tooling costs both the Chevrolet and GMC truck divisions used the same lighter as was found in Chevrolet’s passenger car. It did not match other knobs in the cab. Its double ring chrome head is exclusive to General Motors though it does not carry their logo. They are often seen at swap meets and flea markets mixed with lighter accumulations from all makes. The chrome head is easily unscrewed when a replacement heating element is needed. It will attach to either a 6 or 12 volt element. The in dash receiver also must be changed. GM made a slight difference in element diameters so 6 and 12 volt units could not be accidentally mixed.
1954-1955 Example (above)
In contrast to 1954-1955 Chevrolet trucks, the same year GMC had a position in the dash for an optional gauge. It was here that larger GMC’s had a tachometer or vacuum gauge installed. The 1/2, 3/4 and 1 ton GMC’s usually did not require these engine gauges and a blank-out plate is normally found there. An option here in these smaller trucks is a spring wind clock. It was produced by General Motors and installed at their GMC dealerships.
1954 GMC dash with clock installed (above)
To save production costs, GMC used the clock that was already on the 1953-1954
Chevrolet car. In this way, their investment was limited to a chrome adapter ring that fit in the opening that held the blank-out plate.
This chrome ring has recently been reproduced and is available from most full stocking dealers including Jim Carters Truck Parts. Restorable 1953-1954 Chevrolet car clocks are found at most any medium size automotive swap meet.
There couldn’t be an easier place for a tree to grow. If you don’t move your truck for a few years, trees will find it. As they grow wider, the truck bends to fit!
Here no one steps on a tree at the beginning. Lawn mowers can’t reach it.
It’s free to grow.
With the introduction of the Advance Design Cab in 1947, a new dealer installed heater also became available. When used together this new body was referred to as The Cab That Breathes.
All U.S. manufactured Advance Design Cabs had a row of louvers on the right outer cowl which allowed air to enter the cab interior with the help of the new optional fresh air heater. It was a great improvement over prior years!
As air was brought in from the outside it passed through the heater core. This warmed air usually held less humidity than air inside the cab due to the breath of passengers. The fresh, dryer, air helped prevent the inside of the windows from fogging during very cold days, thus GM said the cab breathed.
This excellent heating system was made even better in 1953 with the introduction of the revised airflow heater. By pulling a knob, at the left of the steering column, a door inside the heater would cover the outside air intake. Now the heater was of the recirculator design. It pulled air from inside the cab so that inside air was re-warmed. Yes, humidity did accumulate quicker and windows could fog but heating the air inside was faster on a cold morning.
Note these pictures of the improved 1953-55 fresh air heater. The driver operated cable was pulled and a door inside the heater shut off outside air. At the same time, a one inch wide door on the case opened to allow recirculation of air to occur. A non-related lever on the case directs the heated air to the floor or above through the defroster ducts.
This ingenious idea by GM engineers now allowed the driver to have a cab that breathed or one that did not.
Hand operated defroster lever, cable for intake door, and the water flow adjusting knob (above)
The knob at the left of the steering column for pulling the cable (above)
The main heater attached to the right inner cowl panel (above)
Side view of heater with water control rod in foreground (above)
A close up of the one inch intake cable operated door on the heater case (above)
 Marty Bozek, Lutz FL.eng261@aol.com |
 Pat Jackson, Johnstown, OHredchevy38@embarqmail.com |
By the mid 1950′s extra income in the U.S. was creating an increased demand for accessories on both cars and trucks. To take advantage of this, the Chevrolet Truck Division introduced one item as a first. It would not appear again on Chevrolet trucks until the mid 1970′s.
The new accessory was the 1954-55 dash mounted clock. To offer the most with the least investment, only the die cast housing was new. The clock was already an accessory on the 1953-1954 Chevrolet car. By combining the two, dealers could market a clock accessory to new Chevrolet truck buyers. The housing was even painted pearl beige to match the 1954-1955 Chevrolet truck interior color.
It fit between the two dash bezels. A paper template was in the box so the dealer’s mechanic or the owner would drill the mounting holes in just the right place.
The housings are not being reproduced. They are in high demand among 1954-1955 Chevrolet truck restorers so the retail prices just keep rising. If you do locate this housing, the correct clock is not difficult to locate. They were on most 1953-1954 Chevrolet cars.
Prior to the 1960′s, trucks were used as work vehicles. On Friday nights, most were parked for the weekend and the family sedan was the transportation vehicle.
It was a conservative era when you bought only basic necessities. A $5.00 grocery purchase was more than most could carry. Finding white wall tires on a truck would have been a rare sight, indeed. Very few cars, except for most luxurious models, would have had white walls even as an option. It should be remembered, that most roads, except highways and those in the main part of town were gravel, dirt, or sprayed annually with tar.
Of course, a dealer would have been happy to install aftermarket white wall tires, if the customer made a specific request. For a price, the dealer would provide any option to keep a satisfied customer and make a few dollars.
On GM trucks, white walls became a factory option in mid-1955, partially because of the introduction of the Chevrolet Cameo and GMC Suburban carrier and also due to more roads becoming paved. These very deluxe pickups, as well as several of the other well appointed 1/2 tons justified a white wall tire for those wanting it all!
Almost none of these deluxe models would have been given their second set of white wall tires. By then, the pickup was older and being used more as a hauler, not for appearance.
Buy Parts for 1934 to 1946 Trucks
The 1947-1955 Chevrolet and GMC came from the factory with left mirror arms on left hand drive trucks. This was particularly important if the truck was to have a large bed that covered the rear window.
To keep sale price low, the right mirror arm was an accessory (dealer installed). It was very important that the dealer place the mirror just right so the actual mirror was viewed by the driver through the lower right corner of the windshield.
To prevent dealer mistakes, GM placed an inner panel in all trucks covering the area were the two holes would be placed. This panel had factory holes, showing the mechanic where to drill. Thus, two exterior holes could always be in the proper place. Yes, the glove box liner would be removed to make room for the drilling.
Inner panel guide for drilling (above)
Outer panel before drilling (above)
It’s surprising that an item placed on almost every 1947-55 Chevrolet and GMC truck has become so impossible to locate. Most collectors have never seen one!
The product is the five inch GM round mirror head. It was originally bolted to the cowl mounted mirror arm on the driver’s side. They were always black and had the pivot on the outside (most round similar non-GM mirrors have the pivot inside the housing).
The pictured mirror head is New Old Stock. Even the zinc plating, which reduces rust, is perfect. The acorn nut can be tightened just right so the head is still hand adjustable yet will stay in place on rough roads.
If almost 500,000 Advance Design trucks were produced each year between 1947-55, where are the original mirrors? The answer relates to the use of the vehicle. These trucks were made for work! Few were garaged. After several years of weathering the mirrors were in need of replacement. This was an easy do-it-yourself exchange and most owners could pay less for aftermarkets at an auto parts store or service station. Few genuine GM replacement mirrors were bought and thus the dealer kept very few if any in stock.
The Chevrolet dealer installed recirculator heater was much different in 1947-48. In 1946 and older plus in 1949 through 1957, they sold the traditional round core design but for 1947 and 1948 it was all different.
The attached photos show the 1947-48 GM recirculator heater. Its rectangular core and vertical mounting studs are reserved for just these two years. To be sure the dealers mechanic installed these accessory heaters correctly, holes were placed in the firewall during the trucks construction.
In this photo of a 1948 firewall, arrows point to the factory holes to make sure the heater is installed just right.
An additional point of interest on this 1947-48 heater:
The defroster appears to be an extra cost item. Note the picture of the truck with the side mounted defroster. Also see the separate heater with a round factory plate covering the defroster position. It appears you could order a style of recirculator heater depending on the climate in your area.
No less than three different mirror arms were used on Advance Design Trucks (1947-1955). Though most vendor catalogs do not reflect these differences, the following should be of interest to those that want their truck restored correctly.
All left mirror arms attach to the same position on the cowl, however two designs were used. In the beginning years (1947-50) the arm pointed at an upward angle. This was much like earlier GM truck body styles between 1936 and 1946.
A change in design began in 1951 with the introduction of door wing vents. With the vent and door open together the mirror head could be hit and broken. Thus, a more horizontal arm was designed and it lowered the mirror. The rounded corner of the wing vent frame could no longer touch the mirror glass.
The right side cowl mounted mirror arm was a dealer installed accessory. Because of the limited space on the cowl (between the door and hood) it was necessary to place a curve in the arm. This brought the mirror head forward so that it could be seen through the lower right corner of the windshield.
1947-1950 Left (MI108) (above)
1951-1955 Left (MI109) (above)
1947-1955 Right (MI125) (above)
We often get requests for a formula to make the Advance Design pickups more freeway friendly. Their original ring and pinion gears were created to make the truck’s six cylinder work well with a load and also keep up with the 1950′s traffic on gravel roads and two lane paved highways.
Though a higher speed reproduction ring and pinion was introduced several years ago, some owners still ask for another alternative to get in the “fast lane”. One method has been used successfully for several years and requires most parts from local salvage yards. Obtain the Borg-Warner 5 speed overdrive transmission from an S-10 pickup. It must come from an earlier model with a mechanical speed sensor (on the side of the case). It can not have the more high tech electronic speed sensor as used on the later S-10 pickups with computers.
This transmission will bolt against the original bellhousing of a 1948 and newer (a nice surprise). The clutch shaft which extends out of the front of the transmission is usually too long to allow the ears to bolt flat and secure to the bellhousing face. Therefore, if this occurs, shorten the tip of the shaft about a half inch and all will fit together. This is a must. Otherwise you can even break off a transmission ear when you begin tightening the four attaching bolts.
The ears that attach the transmission to the bellhousing are usually drilled for a metric bolt. They will need to be enlarged for a standard 1/2 inch bolt as is threaded into the bellhousing.
The V-8 Camaro 5 speed transmission is also similar to the S-10. It is said to not be as low geared and this makes it more desirable. The Camaro shift lever is too far back for the 1948-59 pickup. The bench seat is in the way. To correct this, use the S-10 tail shaft housing and case top cover. This will allow the vertical lever to come through the original floor in the correct position.
The input shaft of the 5 speed will have either 14 or 26 splines. Therefore, the clutch disc must match the transmission and not the 10 splines from the original 1948-1959 truck.
The attractive S-10 boot is still available from GM and the shift knob of choice is from a late model 5-speed Jeep. It screws on perfectly and looks great! The S-10 shifter clears the seat cushion and looks like it was installed by GM.
The next step is the differential. An open drive shaft style will be necessary to match up with the 5-speed but this is a subject for an totally different technical article.
The result of this change is lower RPM’s and speed to keep up with traffic flow on most modern highways.
On the new 216 six cylinder engine, introduced in 1937, the vacuum advance was placed on Chevrolet trucks and cars at the right side of the engine below the distributor. A small metal vacuum line across the front of the engine connected to the carburetor base.
This vacuum advance design continued on trucks through the end of this family of six cylinder engines in 1962, however, on cars a change occurred in 1952. For cars, their engines began with new side motor mounts, not at the front of the block. For the vacuum line to get around this side mount the advance assembly changed position. See photo.
Note: When you see a parts book showing the vacuum advance changes in 1952, they are describing a car not a truck.
Using the 1952-1962 car vacuum advance on a truck will require modification on the vacuum line to a different bend. It will definitely not look correct!
1937-1951 Car and 1937-1962 Truck (left) | 1952 -1962 Car – (right)
by Joel Baumbaugh
Background: About 5 years ago I “upgraded” the engine in my truck from a 216 to a 235. Lately I have felt that I wanted/needed a little more torque (especially while the bed is full of something heavy) and while one option was to rebuild and re-cam my 235 and another was to install a Chevy 350/400 (or 700R), the “popular” literature said that I could also install a GMC 270 or 302. Just to be “different”, I decided to go the latter route.
The Source: I wanted a “running” engine that I could just drop in with a minimum of trouble. The engine I found for my project was a 1959-1962 GMC engine from a School Bus. The bus had been converted into a “camper” and had then caught on fire and burned beyond repair. At first glance, the outside of the engine looked kind of rough. I checked the compression (all cyls. were at 160 lbs./sq.in), looked at the plugs (all light brown), listened to it run (no strange noises) ‘ the oil pressure was 55-60 lbs./sq.in. at idle and the rocker arms/valve area was pretty clean of sludge. Short of pulling the pan, this was as far as I could go. I bought it, brought it home and cleaned it up.
Problems/Solutions: The engine had a LOT of bus-type accessories that I did not want/need. The “massive” front Crank Pulley (the damper pulley assay) had a three-groove pulley ‘ “way” too long! After careful measurement I found that I was able to replace it with a single groove pulley off of a 235 (I replaced the front seal at this time). The water pump shaft was “very” long as well and sported a 2-groove pulley. I removed the pulley and ground/cut the pulley shaft back. The water pump on this engine did not seal against the block and/or head. This one was bolted to a thick steel plate which held a tensioner (for a double groove pulley) which weighed about 30 lbs. (weight I did NOT want) and was bolted to the front of the block. I found a rear plate (and gaskets) for the water pump from a place here in town that rebuilds water pumps. Bolting the water pump directly to the block saved me another ½ inch in engine length. The owner also sold me a flange to press on to the shaft so that I could bolt a new water pump pulley onto the pump (the original Chevy is shaft diameter is ½ inches and the 302 is 3/l8 inches). To find a pulley which would align with the bottom crankshaft pulley required a number of trips to local junk/wrecking yards. I finally found one that was the perfect depth (I’m not sure if it was originally from a Chevy or not). I had to enlarge the center hole to make it fit the GMC shaft.
The 302′s “bus” generator weighed about 80 lbs. I found that the 235′s generator mounting flange’s bolt-holes fit perfectly! However, I “did” need to reverse it and then elongate the mounting holes so that I could slide it forward to align the generator pulley groove with the crank and water pump pulleys.
The carburetor that came with the engine was a joke. It even had a governor on it. I had the option to purchase a better 2-barrel carburetor or to step up a little bit and buy a 4-barrel manifold. I did the latter. I had a (gasp) Ford ‘Autolite’ carburetor in my garage (about 400 CFM) from a ’289′ which I bolted up to the manifold and it works GREAT! – Especially with the stock low-performance camshaft. I also at this time “upgraded” my carburetor linkage. I went to an off-road dune buggy place and purchased a new accelerator pedal and a push-pull cable. Configuring the carburetor linkage from the stock pedal to the new manifold/carburetor would have been a nightmare otherwise.
Radiator: The 302 engine “is” 1 1/2 to two inches longer than the 325 (which is longer than the 216). This means that the radiator no longer fits into its original location. I tried to modify the radiator mount to put the radiator inside. Don’t even try. The radiator needs to mount on the front of the mount. This means that you will have to borrow your neighbor’s “Saws-All” with a metal cutting blade and cut away the top and front cross bracing on the radiator support, the lower front wind deflecting metalwork at the bottom (behind the grill) and drill 6 new holes in the mount for the radiator. The upper support that contains the hood latch will need to have a rectangle cut in it to fit the top of the radiator in it as well. I now have about 2 inches clearance between my water pump pulley and the radiator. I use an electric thermostatically controlled (pusher) fan in front of my radiator. It’s quieter, doesn’t rob the engine of power (better mileage) and the water pump may last longer without the fan blades. Note: My friend and neighbor has a 1951 GMC. I have measured his engine compartment. From his bellhousing to the radiator flange he had 4 more inches to play with, so I’d bet that he originally had a longer GMC engine (he runs a Chevy 235 now), and that he could make the conversion to a 270 or 302 without any cutting being necessary.
Front Mount Yes the 302 engine “is” 1 1/2 to 2 inches longer than the 235. The front mount on the Bus’ 302 was a weird set-up which caused the engine to sit at an angle (like a Chrysler slant 6). This saved some height in the bus’ engine compartment. However, after removing the bus setup spacers, I found that the two bolt holes on the mount (on the bottom of the timing cover/block) were at right angles to the block and aligned perfectly with my truck’s original 216 mount so I was able to exchange them and everything was level ‘ no oil pan removal required! I then drilled two (new) holes through the truck’s cross member, put in longer frame-mounting bolts and added some extra rubber padding (cut from a truck mud-flap) to keep the mount from rubbing on the frame and so far its worked ok.
Rear: The bus engine I purchased was coupled to an automatic transmission. That meant that it had a flex plate (that the converter bolted to) instead of a flywheel. The flex-plate (with the old ring-gear) was MUCH larger than the flywheel I would need. I found a flywheel from a GMC 270 that fit. Although the flywheel’s diameter and the number of teeth are the same as the 1955-1959 Chevrolet, the crankshaft bolt pattern is different between the GMC’s and the Chevrolet’s. The flywheel bolts are different as well (1/2 inch dia. instead of 3/8′s”). Although I tried using an impact wrench, a gorilla on steroids must have put on the old flywheel bolts. I broke a socket and finally had to remove 3 of them with a chisel. The 3/8″ GMC flywheel bolts are not available ANYWHERE. I went to an industrial bolt supply place and bought six more grade 10 bolts. I had the heads machined thinner (like the originals) as otherwise they protrude into the pressure plate/clutch plate area and will cause binding problems. I then carefully shortened the bolts (watch those threads ‘ I put a tap on the inside of the bolt and then backed it off to remove the burrs) to match the original length as they otherwise hit the block behind the flywheel (close tolerances here…).
The pressure and clutch plates and throw-out bearing match those of a Chevy 1955-1959 10- inch set. The 302 had a roller bearing pilot bearing instead of a oillite bronze bushing. I replaced it with another roller bearing and the transmission (its a Saginaw off of a 1969 Camaro) fit in just fine.
I used my original bellhousing off of the 1950 Chevy. The old GMC one was slanted to match the front motor mount. The starter location in the GMC bellhousing was for a larger diameter flexplate and would not work. The GMC starter had the wrong number of teeth to work on the 10″ flywheel. The starter which (I found) works, was a 12 volt 9 tooth (for a 164 tooth flywheel) from a 1955 Chevrolet and works great.
Oil and Water lines: There is an oil line on the front of the block up to the head. This supplies the oil to the rocker arms. Leave it alone. I tied (T’d) into it and put on a 100 PSI oil pressure gage as my Chevy gage only goes to 30 lbs. This engine NEEDS an oil filter. If you block off the oil supply line on the driver’s side of the block you will not get ANY oil pressure in the engine. I “T’d” into the pressure side and connected up my original oil pressure gage (it’s a stretch, but it reaches). Yes, it’s always pegged on 30 lbs., but gives me a warm fuzzy feeling when I look down. The head has an external water line that goes to the thermostat housing. Leave it alone. You can put a “T” in and hook up your temperature gage (with an adapter), but I put mine further down on the block (there’s a fitting there), because it was always showing “cold” on the gage. Be careful of that temperature gage line. It cost me close to $50.00 the last time I had to replace it. The radiator hoses clamped right up although the GMC diameter on the lower radiator hose is one step smaller.
The 302′s distributor had a governor on it and was centrifugal advance only. The bottom of the distributor was different than the Chevy, but my Chevy distributor “guts” bolted right in. I was able to put in a spring kit (the GMC centrifugal advance springs were so thick that they could have been used for front struts on a Honda) and I now have vacuum advance as well.
The GMC fuel pump leaked so I replaced it with a Pep Boys electric fuel pump. I couldn’t find a replacement anywhere locally, so I guess I’ll have this one rebuilt for a “spare”.
I had a split cast-iron exhaust manifold on the Chevy 235. I “may” get a header for this motor in the future, but in the mean time I had the muffler shop split the 302′s three-inch header pipe into the two existing exhaust pipes.
And, how is it?
Well, pretty good. I have a LOT more torque. This means that I can get up to freeway speeds without wishing for bike-pedals for a little more push. I have 36″ tires on 6″ Chevy rims on the back so I’m only turning 2,800 RPM at 60 mph. The larger tires had made the truck a little “logy” getting started with the 235 ‘ now it “steps right out” from a light. I haven’t checked the gas mileage yet. I was getting 17 mpg City and 20 mpg highway with the old 235. I’d guess that I’ve lost about 2 mpg with this engine/carburetor combination.
Future When this old engine is due for a rebuild, I’ll probably buy some “lighter” pistons and a little hotter (than stock) cam. The pistons will help the engine “rev” faster, be easier on the bottom end and will probably result in higher gas mileage due to their weight difference and the higher compression. The cam will help volumetric efficiency and give me a little more torque and higher end. Of course I’ll have everything balanced ‘ IMHO it’s worth the extra money.
I hope that this story helps someone else. Remember the 270 and 302 are “basically” the same engine so I imagine that your situation will be pretty similar to mine no matter what you find. It took “6 hours” using hand tools to remove the old engine and 4 days to put back in the new.
Joel
UPDATE
Since the project above, I decided to rebuild the 302 as it was burning a little oil. I bored the cylinders out .125 thousands (it’s now 320 cubic inches), put in a “Patrick’s” M4F camshaft, and put in “Venolia” 10.5×1 forged pistons. I had everything balanced of course. I had to find and purchase another head as the old one had a crack in it (hence the oil burning). When I got the new (used) head, I pulled out the valves and cleaned/smoothed up the intake and exhaust ports/passages which were pretty rough castings, and then put in new late-model exhaust valves (I went to 1.5″) and hardened seats for unleaded gas, and I’m using Chrysler “440″ valve springs. I’m now running a “Holley” 600 CFM carburetor (vacuum secondaries) with “Fenton” cast-iron headers. When first started up on a dyno (and not really broken in yet) it recorded 286 hp and 362 ft/lbs torque; not bad for a “street” engine; At this time I also put in a T-5 GM transmission from a ’91 V-8 Camaro (the V-8 transmission has better bearings to handle the torque) with a tail-shaft from a S-10 Pick-up (the shifter was almost in the same place) – so now I have a 0.74 overdrive. At 75mph (a fender-slapping speed for the old pick-up) I’m only turning 2,100 RPM; I had a new driveshaft made as the transmission yoke splines on my old one looked worn.
So far, I’m pretty happy with my set-up. Happy “wrenching” everyone;. ..jb
Joel Baumbaugh
| Casting Number | Make | Year | CID |
| 1970 | Chevrolet | 1964-1967 | 292 |
| 2135412 | GMC | 1946-1954 | 248,270 |
| 2193980 | GMC | 1952-1954 | 302 |
| 2324003 | GMC | 1955-1963 | 270 |
| 2324004 | GMC | 1955-1962 | 302 |
| 2404929 | GMC | 1955-1963 | 270 |
| 2192402 | GMC | Military | 302 |
| 289890 | Chevrolet | 1963-1977 | 292 |
| 328575 | Chev/Buick/Olds/Pontiac | 1968-1984 | 250 |
| 328576 | Chev/Buick/Pontiac | 1968-1976 | 250 |
| 328880 | Chevrolet | 1963-1977 | 292 |
| 329990 | Chevrolet | 1963-1977 | 292 |
| 358825 | Chevrolet | 1966-1976 | 250 |
| 3629703 | Chevrolet | 1950-1952 | 235 |
| 366855 | Chev/Buick/Olds/Pontiac | 1966-1984 | 250 |
| 3692703 | Chevrolet | 1950-1952 | 235 |
| 3692708 | Chevrolet | 1950-1952 | 235 |
| 3692713 | Chevrolet | 1950-1952 | 235 |
| 3693374 | Chevrolet | 1942-1949 | 235 |
| 37001481 | Chevrolet | 1953-1955 | 235 |
| 3701946 | Chevrolet | 1953 | 235 |
| 3703414 | Chevrolet | 1954-1956 | 261 |
| 3733340 | Chevrolet | 1955-1957 | 261 |
| 3733813 | Chevrolet | 1958 | 261 |
| 3733946 | Chevrolet | 1954-1955 | 235 |
| 3733949 | Chevrolet | 1953-1955 | 235 |
| 3733950 | Chevrolet | 1954-1955 | 261 |
| 3737012 | Chevrolet | 1955-1957 | 261 |
| 3738307 | Chevrolet | 1958-1962 | 235 |
| 3738365 | Chevrolet | 1960-1962 | 261 |
| 3738476 | Chevrolet | 1958-1962 | 235 |
| 3738813 | Chevrolet | 1955-1963 | 261 |
| 3739365 | Chevrolet | 1958-1962 | 261 |
| 3739716 | Chevrolet | 1958-1962 | 235 |
| 3759365 | Chevrolet | 1959 | 261 |
| 3764476 | Chevrolet | 1958-1962 | 235 |
| 3769716 | Chevrolet | 1958-1962 | 235 |
| 3769717 | Chevrolet | 1959-1962 | 261 |
| 3769925 | Chevrolet | 1958-1962 | 261 |
| 3773949 | Chevrolet | 1954 | 235 |
| 3782856 | Chevrolet | 1962-1967 | 194 |
| 3782858 | Chevrolet | 1962-1967 | 194 |
| 378307 | Chevrolet | 1960-1962 | 235 |
| 3783949 | Chevrolet | 1953-1954 | 235 |
| 3788378 | Chevrolet | 1962-1974 | 292 |
| 3788406 | Chevrolet | 1962-1969 | 230 |
| 3788514 | Chevrolet | 1962-1970 | 153 |
| 3788813 | Chevrolet | 1955-1959 | 261 |
| 3789404 | Chevrolet | 1963-1976 | 292 |
| 3789412 | Chevrolet | 1963-1966 | 292 |
| 3789716 | Chevrolet | 1963-1972 | 292 |
| 3792852 | GMC | 1962-1966 | 194 |
| 3792858 | Chevrolet | 1962-1967 | 194 |
| 3821970 | GMC | 1967-1972 | 292 |
| 3833057 | Chevrolet | 1962-1970 | 191 |
| 3833067 | Chevrolet | 1963-1970 | 194 |
| 3833340 | Chevrolet | 1955-1957 | 261 |
| 383340 | Chevrolet | 1955-1957 | 261 |
| 3835253 | Chevrolet | 1942-1953 | 216 |
| 3835309 | Chevrolet | 1942-1949 | 235 |
| 3835335 | Chevrolet | 1942-1949 | 235 |
| 3835353 | Chevrolet | 1948-1952 | 216 |
| 3835363 | Chevrolet | 1954 | 235 |
| 3835374 | Chevrolet | 1942-1949 | 235 |
| 3835491 | Chevrolet | 1954 | 235 |
| 3835497 | Chevrolet | 1942-1953 | 216 |
| 3835527 | Chevrolet | 1951 | 216 |
| 3835692 | Chevrolet | 1950-1952 | 235 |
| 3835794 | Chevrolet | 1942-1953 | 216 |
| 3835846 | Chevrolet | 1953 | 235 |
| 3835849 | Chevrolet | 1942-1953 | 216 |
| 3835894 | Chevrolet | 1953 | 216 |
| 3835911 | Chevrolet | 1953-1955 | 235 |
| 3835917 | Chevrolet | 1954-1955 | 235 |
| 3835946 | Chevrolet | 1953 | 235 |
| 3835949 | Chevrolet | 1954 | 235 |
| 3836012 | Chevrolet | 1955-1957 | 261 |
| 3836223 | Chevrolet | 1955-1957 | 235 |
| 3836233 | Chevrolet | 1955-1957 | 235 |
| 3836340 | Chevrolet | 1955-1958 | 261 |
| 3836386 | Chevrolet | 1955-1957 | 235 |
| 3837004 | Chevrolet | 1955-1957 | 235-261 |
| 3837012 | Chevrolet | 1955-1957 | 261 |
| 3843363 | Chevrolet | 1953-1955 | 235 |
| 3850817 | Chevrolet | 1962-1978 | 230-250 |
| 3851656 | Chevrolet | 1963-1972 | 292 |
| 3851659 | Chevrolet | 1963-1976 | 292 |
| 3851859 | Chevrolet | 1963-1972 | 292 |
| 3854036 | Chevrolet/Olds/Pontiac | 1962-1976 | 230-250 |
| 3855914 | Chevrolet | 1963-1966 | 292 |
| 3855987 | Chevrolet | 1963-1971 | 292 |
| 3855991 | Chevrolet | 1963-1970 | 230 |
| 3856233 | Chevrolet | 1955 | 235 |
| 3858190 | Chevrolet | 1954-1955 | 235 |
| 3877178 | Buick/Olds/Chev/Pont/GMC | 1962-1978 | 230-250 |
| 3879875 | Chevrolet | 1962-1970 | 194 |
| 3886061 | Chevrolet | 1963-1966 | 292 |
| 3890011 | Buick/Chev/Olds/Pontiac | 1968-1972 | 250 |
| 3890013 | Chevrolet | 1968-1972 | 250 |
| 3892858 | Chevrolet | 1964-1967 | 194 |
| 389770 | Chevrolet | 1942-1951 | 216 |
| 3897702 | Chevrolet | 1942-1953 | 216 |
| 3921770 | Chevrolet | 1966-1976 | 292 |
| 3921967 | Chevrolet | 1964-1969 | 230 |
| 3921968 | Chevrolet | 1964-1976 | 230-150 |
| 3921970 | Chevrolet | 1963-1976 | 292 |
| 828575 | Chevrolet | 1972-1977 | 250 |
| 837751 | Chevrolet | 1942-1949 | 235 |
| 839770 | Chevrolet | 1942-1953 | 216 |
| 8397715 | Chevrolet | 1942-1949 | 235 |
| 839910 | Chevrolet | 1942-1951 | 216 |
| 839931 | Chevrolet | 1942-1949 | 235 |
| 8994256 | Chevrolet | 1964-1977 | 292 |
| 9890043 | Pontiac | 1968-1969 | 250 |
During the Advance Design Truck years, two air filters were available when an order was sent to the factory. The base air filter (no extra cost) was the oil-wetted design from earlier years. The owner was expected to place a thin layer of motor oil on the filter media. Dirt particles would be caught by the oil as it passed through the mesh material. This metal mesh looks much like the material in a kitchen pot and pan copper scraper. The owner was reminded to clean the mesh every 2000 miles for it to be effective.
For an extra $5.00 an improved oil bath air filter came with the new truck. Most everyone who used their GM truck for work duties chose this filter. It required less maintenance and was more forgiving if neglected. GM recommended cleaning in kerosene each 100 hours or 5,000 miles minimum. Part of the filter media actually sets in an oil reservoir that has a pint capacity. The oil is slowly drawn up into the filter material and collects dust particles as the air travels to the carb. * NOTE: For best results use non-detergent oil. Dirt is not held in suspension with non-detergent oil and it settles on the bottom of the reservoir. At the same time held particles slowly sink toward the oil reservoir and accumulate at the bottom. Thus, this filter is always effective due to the oil upward movement. When the oil is changed in the filter pan or reservoir the dirt is also removed.
As with other manufacture’s air filters, they will cause fuel mixture problems when not maintained. A very dirty air filter will restrict air flow into the carburetor and result in increased fuel consumption.
Oil Wetted (above)
Oil Bath (above)
Oil Bath (above)
By January 1949 GM realized there was an engine noise in the new late 1947 Advance Design cabs that needed correction. If a truck customer complained, the dealer was given a solution by modifying a part from a Chevrolet car.
The problem was engine noise entering the cab through the horizontal accelerator rod where it touched the floor hole. On many early Advance Design models there was not yet a pocket to hold a felt floor seal and insulate this rod. Metal to metal contact was inevitable.
The enclosed article is from a GM product service bulletin issued January 31, 1949. It was sent to all dealers.
Note: It is doubtful if all this work required of the dealer in the bulletin was ever very successful. The real noise problem was actually from attaching the back of the accelerator pedal to the accelerator rod. Metal contact here brought noise into the cab and then to the floor where the accelerator pedal made connection. By 1951 a new pedal to rod connection was used (like the car) and the problem was corrected.
Between 1954-1962, Chevrolet produced their famous full oil pressure 235 cubic inch six cylinder in trucks and it soon proved to be one of the greats among engines. However, at the same time a lesser known “big brother” to this base engine was being used. This was the quality built 261 cubic inch six cylinder! This 261 was available only in 2 ton (6000 or C60 series) trucks and school buses. During it’s early years (1954-1957) it was an extra cost option above the standard 235 six cylinder.
In 1958-6192 (the 261 now had a full flow remote oil filter) it became standard in the 2 ton chassis up to 19,000 pounds gross weight. Above that Chevrolet substituted a V-8.
This larger six was not offered in US cars, however there was an exception in Canadian built full size Pontiacs. Their base engine, also produced only in Canada, was the 261 not the V-8 as in the US. This provided basic power, great dependability, and better gas mileage.
Basically, this larger engine was a 235 with the same crankshaft but GM engineers made various modifications to give it extra strength and horsepower. It’s standard bore diameter increased from 3-9/16 inches to 3-3/4 inches. The connecting rods were heavier and attached to increased diameter piston wrist pins.
Its higher lift cam shaft, for better breathing, was shared only with the early 235 six cylinder Corvette. A modified larger Rochester carburetor was also a 261 only feature. Unfortunately most of these larger sixes have long since had their original Rochesters replaced with 235′s and therefore do not perform to their full potential.
In pure big truck form the 261 has a larger thermostat housing holding a double acting thermostat. This is designed to circulate water through the block and head before the thermostat opens to allow hot water into the radiator. Thus, no internal steam hot spots during warm ups, especially in winter. This is particularly important with very cold coolant. Vital engine spots can become very hot before the total coolant becomes hot enough to open a normal thermostat on the front of the block.
| 6 Cylinder Engines | Jobmaster | Thriftmaster |
| Displacement | 261 Cu.In. | 235.5 Cu. In. |
| Bore | 3 3/4″ | 3 9/16″ |
| Stroke | 3 15/16″ | 3 15/16″ |
| Firing Order | 1-5-3-6-2-4 | 1-5-3-6-2-4 |
| Compression Ratio | 7.8 to 1 | 8 to 1 |
| Horsepower | 33.7 (AMA) 148 (Rated) | 30.4 (AMA) 140 (Rated) |
| No.of Main Bearings | 4 | 4 |
| Wrist Pin Diameter | .927 inches | .875 inches |
| Rod Shaft Thickness Front to Back | .595 inches | .595 inches |
| Rod Shaft Thickness Side to Side | .975 inches | .760 inches |
| Crankshaft Journel Diameter | 2.435 | 2.435 |
| Engine Color in trucks | Green -some later Yellow | Gray |
The block and head surface have three pair of matching small “steam holes” that allow any steam hot pockets to vent away from the open water cooled areas between the cylinders that are not solid metal. Of course, this means the 261 must have its own specialized head gasket.
After four years into production, the major quality feature was added to the 261 engine. For the first time a Chevrolet inline six cylinder came standard with a full flow oil filter system. This improvement, used only with the later 261, forced oil through a remote filter cartridge before it reached the engine. It was not like the optional by-pass oil filter system as found on 216 and 235 Chevrolet sixes. This extra helped insure longer life to this larger six cylinder that was often subjected to heavy commercial use.
A full flow oil system has been a characteristic of almost all automotive engines for over 40 years but it was just beginning in the mid 1950′s. With the 261, the disposable filter is remote and not built in as with later engines. It still resulted in a major design improvement.
As with the 235 light truck engine, the 261 came standard with solid valve lifters and an aluminum camshaft timing gear. The passenger car’s 235 was equipped with hydraulic valve lifters and a fiber timing gear for quieter operation.
During the 1955-1962 Canadian Pontiac application the lifters were the hydraulic type, the cam gear was fiber not aluminum, and it did not have the full flow oil filter. These Canadian made 261′s did not add the full flow filter in 1958 as in the U.S.
Visually the 261 looks almost identical to the 235. It perfectly replaces the smaller engine and in stock condition increases horsepower from 140 to 148.
Those planning on a major rebuild or adding performance options to their Chevrolet inline six should seriously consider locating a 261. Often there is no extra cost in purchasing a re-buildable unit, and the results will be rewarding. If you plan on adding additional carburetion, a higher lift cam, or just want additional performance and more lower end strength in your daily driver, the 261 is for you!
Locating and Identifying a 261
Though last placed in larger Chevrolet trucks almost 40 years ago, this now scarce engine can still be located and often at a price no higher than for the smaller 235. Many still remain in the original Chevrolet trucks and are now setting in salvage yards or behind farm buildings. In Canada, the big Pontiac cars are sometimes in the back rows of more isolated older wrecking yards.
Don’t overlook the wrecked and badly rusted Chevrolet cars of the 1940′s and 1950′s, particularly those showing signs of some past exterior customizing changes. The Chevrolet enthusiasts of that era knew about the 261 and its potential for added performance. Some of these will already have had extras added such as a higher lift cam shaft, extra carburetion, or dual exhausts.
When you have found what you suspect might be a 261, check a few specifies to verify you have the real thing and not the visual almost identical 235. Casting numbers, not stamped numbers, on the 261 head are very visible beside the rocker arm cover. A different set of numbers relate to the 261 block. These seven digits are located on the right side between the fuel pump and starter except for 1954 where it is located forward of the fuel pump. See chart below.
| YEAR | ENGINE SIZE | BLOCK NUMBER | HEAD NUMBER | |||
| 54-55 | 261 | 3703414 | 3733950 | 3703570 | 3836850 | |
| 55-57 | 261 | 3733340 | 3837012 | 3703570 | 3836850 | |
| 58-62 | 261 | 3739365 | 37369717 | 3769925 | 3836850 | |
Watch for the “Captain’s Bars!” The 261 has two pairs of parallel raised 3/4 inch long bars cast in the block. This is not seen on a 235 except 1954. One pair is above the starter and the second pair is at the top middle of the left side of the block very close to the head. See photos below. The one exception is the early 261 produced in 1954 to mid 1955. It has only one “Captain Bar” above the starter but keeps the pair on the left side.
Most used 261 blocks are rebuildable, however often their cylinder heads will have a few very small cracks in the combustion chamber. This is typical due to occasional abuse of over heating in past years. If you choose not to add to your expense by having the cracks repaired, an alternative exists. The more common 235 head is the same except for the three pair of internal steam holes. These can be manually drilled to make the water flow just like in the 261! Sorry, but some 235 heads can be cracked even more than the 261 because they lack heat releasing steam holes.
“Warning” When Installing a 261!
The stock remote filter system has two very visible 3/4″ lines threaded into the block. One is from the pump to the filter and the other from the filter back to the block. Oil must leave and return to the engine by these lines (even if the filter is eliminated) or the engine will fail from lack of lubricant. Many 261 engines have been quickly seized after persons plugged the two oil line holes. They had many years experience on Chevrolet engines without the full flow oil system. Some thought it was an easy fix to just remove the 3/4″ lines if one was leaking and cap the holes. This procedure was acceptable on the older 216 and 235 but never on the 1958-1962 261 truck engine.
Occasionally we hear owners condemning the closed drive shaft system used in the 1/2 ton trucks prior to 1955. After questioning the negative comment, we almost always discover the real criticism is the low gearing of the ring and pinion in the differential. Yes, this lower gear ratio was created more for slower roads of year gone by, but it is by far not a poorly designed system. In fact, it is questioned if there has ever been drive shaft and u-joint combinations that exceed the durability of this GM quality engineered closed unit.
Over 50% of the surviving older 1/2 ton pickups continue to use their original closed systems. Of these, the majority have had little or no servicing other than keeping lubrications in the transmission and differential.
Consider this when you realize the last GM closed drive shaft system was produced in 1954. Many others have been in irregular service prior to the 1920′s. Also remember that many 1/2 ton pickups were often given abuse far in excess of the manufacturer’s recommendations.
What modern open drive shaft system has been able to compare with this unsurpassed record? None!! Sure, the newer open u-joints are easier to change. They better be. They require attention or replacement so much more frequently!
We recently received the following comment from John Berkeley Ball. He also confirms the quality of the General Motor’s 1/2 ton closed drive shaft and differential.
Dear Jim Carter
Thanks for your excellent articles. One very pertinent point I feel that you should mention about closed drive shafts is their absolute impervability to rear spring wind up. Used on the farm over soft ground with heavy loads, you could not afford to send your rear end into drive breaking pulsations every time you lost traction, whether the shocks were worn out or not (some were single action any way). What a huge advantage over the Hotchkiss rear end! this is an often unknown design attribute that Chevy engineers were unfoundedly maligned for – at least by today’s city slickers…
John Ball
You may relate comments to this web site or Mr. Ball direct at john_ball@telus.net.
Designed by an aftermarket company to keep an over tightened valve cover from leaking motor oil down the engine sides. A metal band is pushed over and around the base of the valve cover. Brass U-brackets are then secured by the two valve cover studs. This creates equal pressure around the valve cover perimeter to stop the leaks down the side of the engine.
Scott states he has seen these brackets on another 216 engine. Maybe a company in that area once offered them at local auto parts stores.
This photo was taken by Scott Golding, a resident of Western Nebraska.
E-mail scottandbetty@hotmail.com. Scott states he has seen these brackets on another 216 engine. Maybe a company in that area once offered them at local auto parts stores.
Your opinion is welcomed.
Chevrolet introduced their basic nine inch single disc clutch and corresponding diaphragm pressure plate in 1938. This pair was used in their cars and most 1/2 ton pickups with three speed transmissions through 1953. With about one million of these vehicles sold annually, one can quickly realize the high numbers of this clutch system that was at one time on the highway.
Even in 1954 with the introduction of the larger ten inch clutch disc and modified pressure plate on the new 235 six cylinder, the original design continued to sell very well as aftermarket replacements. Today, they still have a strong demand even though the majority of these over fifty year old vehicles are history. Most auto part stores now keep a pair in inventory for their walk-in customers.
To add even more validity to this clutch’s durability, GM reintroduced it in the late 1960′s. General Motors was a major producer of full size passenger buses and the demand for most having the optional air conditioning was becoming strong. Almost all new buses would now be equipped with the option. The original small nine inch clutch was combined with the newly engineered large bus AC compressor. Once again, this proven clutch was serving automotive needs!
Therefore, if you find a source for new or core clutch assemblies used from the late 1960′s to at least the mid 1970′s in GM buses, they will also fit 1938-53 cars and small trucks.
The door window is cranked up tight in the cloth channel and off you go on your daily errands. Suddenly, the glass begins to slowly lowers as you drive over side roads or contact a rough surface. In comes cold air, rain, and wind! Even the window handle turns. What’s this all about? Do you tape the window closed or wire the handle so it will not turn?
You have a window regulator spring problem! This large 2″ diameter round spring has either broken or become disconnected.
With no spring tension on the regulator, the weight of the glass creates the lowering of the support arm and window. Sorry, there is no good fix other than removing the regulator from inside the door. The picture below shows this circular Clock spring. It must be large to hold the weight of the glass panel.
Prior to the mid 1960′s, motor oil did not have the modern detergent additive. Therefore this type engine oil didn’t keep dirt particles in suspension. Foreign material would slowly settle to the bottom of the oil pan and on other flat surfaces such as the valley of the head.
If you ever removed an oil pan from a 50 year old engine that has been setting, chances are good there can be up to 1/4 inch of sludge in the bottom. This is not a bad thing! The non detergent oil has allowed the dirt to settle. As most 60 year old engines did not have an oil filter, this dirt settling was what should happen to increase the engine life.
The problem begins when a new owner wants to get his old vehicle running. He installs plugs, points, back-flushes the cooling system and changes oil. Oops, he probably adds detergent motor oil! The dirt deposits now begin to slowly go back into suspension. Unfortunately with no oil filter the dirt stays in the oil and shortens the remaining life of the engine.
Prior to about 1962, Chevrolet trucks were equipped with round straight through mufflers. These units reduced back pressure and allowed the engine to breathe to its full potential. This caused a little extra exhaust noise in comparison to the larger more engineered oval car mufflers but trucks were for work and power.
About 1950 truck mufflers were given slightly larger inlet and outlet pipes. This allowed increased air flow which related to the slightly larger carburetor installed that year.
During the late 1960′s the Chevrolet truck Master Parts Catalog no longer listed mufflers. It appears they discontinued these units and left them to be provided by auto parts stores. By about 1995 the larger 1950′s straight through muffler was the one style available and any remaining older pipes were modified to fit 2″ inlet and 1 7/8″ outlets. Length is about 20 ½ inches.
The cars were lower to the ground and thus, required an oval muffler. This oval shape allowed it to be higher and less likely to hit an object on the road. Trucks were high and a round muffler was satisfactory.
Correct copies of these mufflers are available from Jim Carter’s Classic Truck Parts and a few other full stocking GM truck dealers.
During the 1940′s through 1950′s placing pin stripes on automobile wheels occurred on most all brands. It was an inexpensive touch that added a little flair to the appearance of a new wheel. The stripe could be added quickly with a machine on a rotating wheel. The factory didn’t need a human as on the body stripes.
GM was no exception. They had been striping most new car wheels for almost 10 years. Beginning with the 1947 Advance Design trucks, this striping even was used on ½ tons that had the deluxe package (not the standard models). This extra was continued through the 1947-1955 body style.
The attached photo shows a used original never repainted 16″ 1/2 ton deluxe wheel. Note how perfect the 3/4″ stripes are applied. With the addition of the small chrome hub cap, the wheel drew attention
The closed drive shaft ( on GM 1/2 ton, 1937-54) is supported at the front by two bushings. As these wear egg shaped over many miles, the drive shaft begins to move up and down. This ruins the grease seal and causes the u-joint to begin rubbing the “bell”. Thus noise and vibration!
Finally, with a bad seal, the differential fills with transmission grease running down the drive shaft starving the shifting gears. Then, the rear wheel seals leak, the brake shoes become oil soaked, and finally the u-joint flies apart from rubbing the bell.
Catch the developing problem early and save much expense and down time. Install what is sometimes called an “Okie Bushing”, an aftermarket, non-GM repair. This is a quick, permanent fix that does not require tearing down the differential!
Remove the u-joint bell retainer and slide this bell back, exposing the u-joint assembly. Disassemble the u-joint by removing the four bolts. The rear u-joint yolk can now be slid off the 17 drive shaft splines, exposing the grease seal in the drive shaft.
Pull out this seal and the front egg shaped bushing from the torque tube. Sometimes this bushing is difficult to remove and special pullers can be rented. Otherwise, call Jim Carter’s Truck Parts at (800) 842-1913. They have these pullers made.
Press in the long Okie bushing – seal first. Placing a wood block over the bushing end and tap into the drive shaft housing (torque tube) with a hammer. This action will then press the other original rear bushing back out of position. The new Okie bushing will now hold the drive shaft in perfect alignment, as when the vehicle was new.
They used to advertise this as a permanent half-hour fix. This is optimistic but so much easier than disassembling the differential as the Chevrolet dealers did 50 years ago.
Before the modern Positive Crankcase Ventilating System (PCV) most automotive engines breathed externally and removed their excess products of combustion into the atmosphere. It was a standard of the industry!
The lower end of the engine (below the pistons) had an attached draft tube that extended outside and below the block. It released blow-by from worn piston rings and other pollutants created from the crankshaft turning in hot motor oil.
The upper end of the overhead valve engine also must breathe. On early Chevrolet and GMC inline six cylinder engines, the venting is usually in the valve cover through factory slots. When an add-oil cap exists on this cover, it seals tight. It does no breathing.
On 1955-62 Chevrolet 235 six cylinders the valve cover slots were illuminated. It is assumed badly worn engines at high RPM leaked oil at these slots. The venting requirement was now moved to the oil cap. These redesigned caps have two features. They cover the add oil hole and vent the upper end of the engine. Their disadvantage is their internal filter can clog with oil vapors and dirt from a badly worn engine. This type venting cap must be kept clean!
The following photos show venting methods on early Chevrolet and GMC engines. Note the oil and breathing cap on the later six cylinder Chevrolet engines.
1937 through 1953 216 sealed oil cap (above)
216 valve cover vent slot (above)
1954 Chevrlot Vents (above)
1955-1962 non vented cover (above)
1955-1962 vented oil cap (above)
1963-1972… 230 and 250 with PVC system (above)
When shifting into 2nd gear finds your knuckles contacting the glove box door, repairs are needed
Chevrolet did not plan on these 3 speed transmissions to be in use over 50 years so repairs in this area were not often discussed by GM. You can fix it anyway!
Remove the flat plate with the shift lever from transmission by taking out the 4 retaining bolts. (Be sure to replace this plate with cloth or cardboard so no foreign object falls inside.) Take the shift tower from the flat plate top by removing four retaining bolts. The shift lever and its 2 1/4 inch tension spring can now be taken from the tower.
Inside the top of the tower is the worn brass bushing causing most of the shift lever slop. A replacement with tension spring can be obtained from Jim Carter’s Truck Parts and most of their full stocking dealers.
Sorry, exchanging the brass bushing will not solve all the problem. The long horizontal pin, through the shift lever ball, needs to be replaced. The pin will probably be worn on each end and needs replacement.
Using a drill bit is a good option for a new pin. If a 1/4 inch drill bit easily moves into the shift lever ball, move up to the next size. (Maybe as much as 9/32 inch drill bit). Use it to drill the hole oversize, then use this same drill bit as the new pin. After drilling, remove the drill portion on the bit, and you have a nice hardened pin! Note: do not cut the drill bit until you know the exact length needed. Get a correct size by turning the shift tower upside down and measuring the distance between the two notches to the tower walls.
The term artillery wheel is a nickname adapted from a scalloped type wheel often seen on US military vehicles in World War I. The similar appearance at a distance to GM’s scalloped steel wheels quickly gave them the name artillery.
On GM trucks, this style was first used during 1934-36 as a stock six bolt 1/2 ton 17 inch wheel. It was much stronger than the existing wire style wheels due to it being less susceptible to bending when hitting a large pot hole or sliding against a curb.
Though this 17 inch unit was discontinued on 1/2 tons for 1937, a redesigned 15 inch artillery began as GM’s stock wheel on that year’s 3/4 ton truck. It was stronger and wider but was still a non-split rim design. This remained the GM 3/4 ton wheel through 1945. By 1946, six bolt wheels on trucks were limited to 1/2 tons. The 3/4 ton would now have 15 inch 8 bolt split rims which remained stock into the 1960′s.
Today, we sometimes see 1947-59 GM 1/2 tons equipped with these early 15 inch artillery 3/4 ton wheels even though they were not placed on factory trucks after 1945. To many, they provide a unique appearance on the later 1/2 tons and will still hold the trucks current hub cap.
Regular 16″ Wheel (above)
1934-1936 17″ Artillery Wheel (above)
1937-1945 15″ Artillery Wheel (above)
About 10 years after the introduction of GMC’s new inline six cylinder engine in 1939, General Motors issued a ‘Product Service Bulletin’ in regards to a recommended improvement on the 228, 248, and 270. It appears the manufacturer discovered a weakness that shortened the life of the engine timing gears. This recommendation was made for enlarging the oil supply hole leading to the meeting point of the two gears. The attached dealer bulletin was issued January 31, 1949.
This is especially interesting considering over a million GMC trucks with these engines had been built prior to this. The number includes the five years of military large trucks that were used during WWII under very abusive off road conditions!
From 1934 to 1959 GM 1/2 tons came from the factory with a tie rod assembly that extended side to side to almost touch the front wheels. With everything stock, the tie rod sits about 3/4 inch from the inside of both original six hole wheels and all fits just right.
A problem exists when someone attempts to add a more modern wheel. For example, the mid 60′s and newer 4×4 wheels have this 6 hole bolt pattern but their width causes them to contact the end of original long tie rod. Changing from the approximate 4-1/2 inch original to at least a 6 inch width just won’t work.
Solutions for adding a more sporty wheel are very limited with the original suspension. One almost unknown method is to replace the original GM multi-piece tie rod ends with the more modern knuckle ends introduced in the 1960′s. There are currently available and are 3/8 inch shorter on the outer end giving that much extra room for a slightly wider wheel. (It is not recommended that flat washers be placed over the stud between the wheel and drum as this can cause breakage.)
This GM six bolt pattern is also shared with several Japanese pickups. Some very attractive more narrow aftermarket wheels have been produced for their imports in past years.
If you use a recently manufactured 216 water pump and combine it with the optional larger OEM radiator fan, a slight modification is necessary. The fan rivets will not clear the edge of the pulley hub. You must cut four notches in the hub for rivet clearance. Water pumps in the last five years appear to lack these notches.
Note: These larger fans, 18″ long, were optional on smaller trucks and always came on the 1 1/2 ton’s. It is the 15″ fan that will usually be on small trucks and passenger cars.
Comments courtesy of:
Bob Adler, Stephentown, NY.
bobadler@nycap.rr.com
Notice the four notches cut on the outer rim of the hub. (above)
Hub and Fan. (above)
Sometimes overlooked by mechanics and restorers is a small vent in the rear axle housing. This part is necessary to keep internal pressure equal to the outside atmosphere. Thus, as the internal temperature of the differential warms during use, any expanding heated air is vented and no pressure occurs. This saves wheel and pinion seals from leaking.
Check for this vent in your truck. From years of abuse many vent assemblies are missing. A sliding log chain wrapped around the axle housing for pulling is a way many vent assemblies were accidentally removed. The owner usually didn’t know the damage has been done or that a vent ever existed. Now, the small hole that once held the vent assembly is able to take in water. This is certainly not good for the internal differential parts.
One series of the famous “drop out” GM differentials was used between 1946 and 1972 on 3/4 and 1 tons. The complete assembly (often called a pumpkin) will interchange during these years with no alteration.
The highest gearing in this series is the 4.10 ratio and is found in most 1967-72 3/4 tons with automatic transmissions. Therefore, those “low gear blues” often associated with 3/4 and 1 tons during the late 1940′s and 1950′s can be greatly improved with no visible exterior changes. Originally these older trucks had a ratio of 4.57 in the 3/4 tons and 5.14 in the 1 tons.
Once a 4.10 pumpkin is located (usually in a local wrecking yard) it is a basic interchange requiring little more than new gaskets and gear grease. Your truck’s personality is now changed!
For those wanting a new 4.10 ring and pinion, production was begun again in April 2000 (at this time they also produced a 3.90 ratio). In order to use these assemblies in the 1940′s and 1950′s truck, they must be attached to the differential carrier from a 1964-72 3/4 ton. Only then can the complete pumpkin be installed in the older truck.
The only negative to this changeover is if you are hauling a ton of gravel up a mountain road with the original smaller six cylinder!! In this example a lower geared differential is best.
The 1955-59 Chevrolet and GMC originally came with a non-metal shield to direct light into the ignition switch to the key slot. This shield is almost always missing after fifty years. Most shrink after twenty years and fall from the switch. The accompanying photos show this snap-in shield in place. Even the die cast opening is notched on all switches to hold this non-metal plate. The illumination from the snap-in light bulb socket directs the illumination through the small lower opening, then to a hole in the switch, and finally to the key slot in the ignition cylinder. When the driver enters a 1955-1959 GM truck at night, he pulls the headlight switch and the illuminated key slot shows where to place the key.
With the introduction of the Advance Design panel truck in mid 1947, it was soon evident that a serious safety hazard existed with a few companies, some night deliveries required the rear double doors to be open. This prevented the taillight from being seen! No doubt this caused some accidents particularly with a fast vehicle coming from behind, with dim older bulb headlights.
The General Motors Product Service Bulletin (issued regularly to dealers) dated May 31, 1948 relates to this condition. Though it is dated over a year after initial panel truck production, it warns dealers and offers an alternative to lessen this unsafe condition.
The following is a copy of the suggested GM modification to correct the problem. As this particular product service bulletin was issued in Canada for their Canadian dealerships, it is not known if the announcement was also made to dealers in the USA .
It may be of interest that this extra light #916877 also used the same number in the Chevrolet Master Parts Catalog as the left 1939 car taillight assembly. (It appears GM used no extra tooling to create this new panel truck extra.) Note: They even requested the dealer to solder the water drain hole in this car light and re-drill because of its different mounting position.
The following is taken from the May 31st, 1948 Product Service Bulletin.
Rear Signal Lamp Released – All Panel Trucks
Some requests have been received for a signal lamp, which would be visible on Panel trucks when the rear doors are open at night. This type of lamp, which will operate in conjunction with the tail lamp, can be mounted on the roof panel, as shown in Fig. 77. The material necessary to make this installation is shown in Fig. 78.
Fig. 77 (above)
Fig. 78 (above)
Fig. 79 (above)
Of the material listed in the chart, the insulated wire, the metal plate, and the two rubber washers are to be made up locally. The dimensions for the metal plate are shown in Fig. 79 and the dimensions for the rubber washers are given in fig. 80. Assemble the bayonet connection to one end of the insulated wire and the eye terminal to the opposite end. A drain hole will be found in the side of the lamp rim. this should be plugged with solder and the same size hole drilled in the bottom of the rim for drainage.
Fig. 80 (above)
The installation procedure is as follows.
1. Center the metal plate, Fig. 79, nine inches from the rear drip molding over the center of the rear doors.
2. Using the plate as a template, drill two 7/32″ holes and one 3/4″ hole in the roof panel.
3. Drill a 7/16″ hole in the roof left side rail, “A” Fig. 81, and another 7/16″ hole “B” in the lower side panel behind the left rear door.
4. Place the two rubber washers over the studs in the lamp and the rubber grommet around the wiring. Assemble the metal plate on the inside of the roof panel and install the lamp using the attaching stock supplied.
5. Connect the 6 ft. of insulated wire to the plain wire in the lamp by means of the bayonet connection. Note: A two filament bulb is used in the lamp. One 3 C.P. and the other 32 C.P. The plain wire connects the 3 C.P. filament. Cut of the other wire.
6. Thread the insulated wire through the holes drilled at “A” and “B” Fig. 81. Install one of the wiring clips under one of the screws in the rear door upper striker plate “D” and the other clip under the screw at the rear of the belt strainer “C”. Compress the clips so that they fit snugly around the wire.
7. Connect the wire to the tail lamp switch “E” at the same terminal as the black tracer wire.
Fig. 81 (above)
Beginning in 1951, the rear bumper became an option on both Chevrolet and GMC pickups. This required a change in the standard left tail light bracket. The tail light assembly was now unprotected without the bumper. GM created a new bracket design that brought the tail light slightly ahead of the rear edge of the stake pocket.
In this way the tail light was not hit when the pickup backed against a loading dock. Of course, when the truck came with the now optional rear bumper, the tail light bracket remained as earlier years.
The non rear bumper tail light bracket is not being reproduced. For the perfectionist, it will require some hunting to uncover one of these rare assemblies. Most restorers want the optional rear bumper and thus there is little demand for this forgotten bracket.
1947-1950 (above)
1951-1953 (above)
1947-1950 (above)
1951-1953 (above)
1947-1950 (above)
The Chevrolet and GMC left commercial taillight used during 1947-1953 is an excellent example of GM’s conservative thinking towards trucks. The number one purpose for trucks was work! Therefore, if a part had been very successful on a prior body design, it just might be adapted later as a part in some new styling. Savings were in production costs and tooling. The results were still a good practical part for a working vehicle.
This type of thinking it shown in the Advance Design 1947-1953 pickup taillights. The same light assembly had not only been in use on trucks since 1940 but the red lens and chrome bezel was first used in all taillights on the 1937-38 Chevrolet passenger cars.
With the introduction of the new 1947 body style, this same six volt light continued to be used. It was now turned 180 degrees, so that the clear license light lens was at the bottom, and did not shine upward as in prior years. This allowed for a smaller taillight bracket with low mounted license plate. On earlier models the high positioned license caught the wind. This plus the use of trucks on rough terrain often caused bracket failure. With the left light illuminating the license plate, the optional right taillight did not have or need this lens opening.
Because the same lens was used on the 180 degree reversed taillight in 1947-1953, the red lens letters were now upside down. This was not a problem to GM as trucks were for utility purposes. Changing the lens tooling just to make the cast letters show upright was not a consideration. The red lens sold by authorized Chevrolet or GMC dealers normally had STOPRAY block letters at the top and either GUIDE letters in script or “STIMSONITE” in block letters at the bottom. In 1949 GM changed the red lens from glass to plastic. This thinner material reduced overall weight and gave a brighter red when light passed through. The various aftermarket lens manufacturers also followed GM’s procedure. Even their lens lettering is reversed when placed on the 1947-53 trucks. It appears they also designed this lens with the 1937-1938 car in mind.
The light on the pickup and larger truck has a rectangle shape with dimensions 4 inch high x 2 1/2 inch wide. An authentic 1940-1953 GM light bucket will have the block letters GUIDE-MADE IN USA stamped on the back. These letters are not visible when attached to the factory taillight bracket. In 1947-1953 the 1/4 inch block letters STOPRAY were stamped in the top of the light bucket. These letters, prior to 1947, had been stamped in the area at the rear of the license lens on the opposite end when the bucket was reversed. In this way “STOPRAY” is always seen on the top in this series of taillight. The running light bulb (illuminating both the license and red lens) is three candle power. The stop light bulb, positioned behind the center of the lens, is 21 candle power. The bezel was chrome over the black bucket until copper shortages occurred in 1952-1953 due to the Korean War. The bezel then became black.
One minor change in this design over its early years was the reversing of a very small water drain hole in the lens retaining bezel. Engineers knew this water escape hole would be needed for drying and to drain moisture from within the bucket as the cork bezel gasket began to deteriorate within several years. This drain hole was centered in the bottom of the original light bezel; however, between 1947-1953 when the light was reversed, the bottom drain went to the lower right. This was due to an internal securing bracket welded the middle of the bezel and preventing there being a place for a center drain hole.
This taillight as used on pickup and larger trucks is mostly unprotected from the elements when located beside or under the bed. Tests quickly showed that some type of seal would be necessary in the hole where the two light wires from the bulb exited the taillight. As a modern rubber seal had not been perfected, GM skillfully came up with a solution. An approximately 2 ft. long, 5/16 inch diameter cloth woven black lacquered tube was inserted one inch into the bucket taillight wire hole. The inside end was flattened on the two wires with a heavy metal staple. This prevented the loom from being removed, protected the wires, and prevented water from entering the housing.
With the total redesign of the step bed in 1954, the six volt taillights were also changed. They became round four inch diameter units with one light bulb having two filaments of three and twenty one candle power. The lens retaining bezel was chrome plated on the more deluxe truck, painted black like the bucket on the standard models. The clear license lens was in the bottom of this bucket to illuminate the plate below. With the optional rear bumper on pickups, the license plate moved to the middle of the truck and the taillight did not have the lower lens window. As before, the right light was an option.
Taillights on the panel truck, suburban, and canopy express (single unit bodies) had no similarity to those on the pickup and big trucks. On panel trucks a single to light was placed near the center of the left “barn door”. The lens retaining bezel was chrome with dimensions of three inch high by 4 1/2 inches wide. A decorative stainless two inch wide strip on top of the housing has the stamped letters GUIDE R17 T. A single socket in the housing holds a double filament bulb of three and 21 candle power. The license plate bracket is secured to the rear of the bucket and allows illumination of the tag below the light. During these Advance Design years, this panel truck lens and chrome bezel were also used on the rear fender of the Harley Davidson motorcycle.
The canopy express and suburban bodies also displayed a single taillight with suspended lower license. It was attached to a cast metal swing bracket on the center of the tailgate. This bracket plus a special vertical connecting rod made up an ingenious design. When the tailgate was opened to its horizontal position, the taillight and license would swing 90 degrees so that it could still be seen by the following traffic.
This round taillight was normally black with a 4 3/4 inch diameter chrome lens retaining bezel. Inside are two sockets holding individual bulbs of 3 and 21 candle power. Block letters on top state GUIDCOLITE STANDARD. To save costs GM adapted this light from a prior application. It had been the GMC pickup taillight from the late 30′s through 1946. During these Advance Design truck years the light was also found on Chevrolet station wagons.
As the 1950′s progressed, there were increasing requests for directional signals. This soon became a GM dealer installed option to be placed on new or pre-owned vehicles. On pickups it was easy! The option included a right side light and bracket closely matching the standard left assembly.
Adding a turn single option today 1947-1955 single unit body created problems for GM designers. Neither the single factory taillight on the double door or the center unit on the tail gate were in a good position to be matched with a second live assembly. GM solved this by offering a turn signal kit containing two matched taillights. These were dealer installed beside the vehicle belt line near the doors and above the edge of the tailgate. These small bullet shaped lights were actually from a 1939 Chevrolet passenger car. It appears GM dusted off the ten year old car taillight tooling and kept expenses on this option to a minimum. The letters “DURAY” are stamped in the top of the painted housing. The chrome bezel retains a 2 5/8 inch diameter red glass lens. Due to a small water drain hole, there is a right and left on these turn signal lights.
NOTE: It is interesting that both the pickup truck and the tailgate lights, each developed during the late 1930′s, continued with separate bulbs and sockets for each filament. The door mounted oval panel truck light, introduced in mid 1947, was provided with a more modern double filament bulb in one socket.
A redesigned parklight assembly was started with the introduction of the 1947 GMC advanced body style. It was placed in the front fender 3-1/2 inches below the headlight ring. A 2-5/8 inch diameter bezel held a domed glass lens to its housing by two barrel screws.
The unit was not meant to be a combination turn signal and parklight assembly and held a 3 candle power single filament 6 volt bulb. As with other car and truck parklights prior to 1968, it did not operate when the headlights were on.
This round lens and chrome ring soon found other uses. They were placed on the parklights of Chevrolets new Corvette sportscar between 1953-1962! The ring also held a different lens to the rear of certain GM cars when they had the optional backup light assembly.
During 1952-1953, GMC used an enlarged parklight assembly only different than the 1947-51 unit in size. Dimensions were increased to 3 inches diameter to give more light area. It fit in the same front fender location and the securing ring was now painted white as was most other 1952-53 GMC trim during the Korean War shortages.
This larger glass was shared with several larger GM cars as their parklight lens. The same rings, however, were chromed. These chrome rings were also used to hold a different clear lens on several GM cars for their back up lights.
When viewing older GM cars and trucks we see both colors of park light lenses. There seems to be no consistency that gives us the proof of what is actually correct, however, it is easy as remembering a year.
Beginning in 1963, federal regulations required park lights to show an amber color. Today, companies reproducing original clear lenses find it easy to run more in the same die using an amber additive. Therefore, in GM trucks most 1954-62 clear lenses now can be found marketed with an equivalent amber style.
One exception is the 1969-1970 Chevrolet truck. Originally it came new with clear lens but behind them are amber park light bulbs giving the required color appearance when illuminated.
Our seat cover kits are produced with an emphasis on originality. The materials are top quality for many year’s service. Seams, ribbing, etc., are based on original seats.
We recommend that installation be done by a professional upholstery company. However, if you wish to do it yourself, here are several important steps to follow:
1. Seat springs must be in original condition. No breaks, sags, etc.
2. Over springs, place one layer of burlap.
3. Over burlap, place two layers of cotton padding. Cotton must extend down over edges of outer springs.
4. Place vinyl cover over padding. Stretch evenly to eliminate wrinkles. Press special C shape clips at rear of springs to permanently hold cover in place.
5. If clips are put in place with pliers, cover the end with tape or equivalent to lessen chances to vinyl tears.
6. Wrinkles from storage will normally disappear in several days.
Two major changes occurred in 6 volt General Motors sealed beam bulbs since they were first installed on vehicle assembly lines in 1940. The perfectionist restoring his truck to exact original specifications must have the correct sealed beams for his year. In very competitive judging, it’s these details that can make a difference. No doubt, replacement bulbs from a GM dealership with slow sales could sometimes be placed on newer vehicles a few years after the units were discontinued, however this article is based on bulbs you would have bought new from the factory during that particular year.
1940 through about 1946 – These sealed beams had a double filament small bulb built inside. The large glass reflector in the back was sealed from the elements. It stayed bright until the bulb burned out. It was not like earlier open reflectors that could tarnish with age. The assembly comes with a metal black back attached. If the outer glass gets a rock hole, the light continues to work well. The filament is still encased in the smaller argon gas filled glass bulb (see photo).
1940 through about 1946 (above)
About 1946 through 1955 (below)
The first sealed beam bulb, as we know it, was introduced after the end of World War II. Between the reflector and the outer glass covering is the open unprotected filament (no small internal bulb). The total interior is filled with argon gas to protect the filament from air which causes instant burn out. When a rock places a small hole in the glass the filament is ruined.
The big visible difference in this first real sealed beam bulb and today is there was no aiming bumps on the outside as in later years. The dealer aiming equipment had not been invented.
1955 and newer…(above)
Beginning in 1955 the 6 and 12 volt sealed beams have three glass aiming bumps molded in the edges of the lens. The bumps were needed by new light aiming equipment provided to GM dealerships. All of these GM bulbs with aiming bumps have the letters T-3 molded in the center of the glass lens. Most will also have the word Guide at the top of the lens.
Note: These modern bumps will interfere with properly attaching the chrome bezels on a 1940 headlight bucket as well as a 1937-1939 bulb light that has been converted to sealed beams. The bezels were not designed for the bulb still 15 years in the future. The 1940 GM vehicle owners will have a long hunt to find sealed beam bulbs without the three bumps.
The first design of the 4-speed synchronized truck transmission, introduced in 1948, was used through about 1965. About mid series, when the dealer installed backup light increased in popularity, a special switch was attached to the base of the floor shift lever. This was the only location possible as there is no external linkage on a 4-speed.
No doubt regular floor contact with shoes and boots shortened the life of this small electrical switch.
When observing restored 1947-1953 Advanced Design trucks, we rarely see the removable dash parts painted correctly. Though at least half the owners paint these parts to their personal taste, many truck restorers want the dash appearance as original. Surprisingly, we rarely see two alike even on trucks that are said to be restored just like they left the factory.
The following is factory correct! With a little extra effort your dash can look just like what the original owner saw 50 years ago.
1947 to Late 1951
This is the early years of the series before the Korean War shortages. At this time, chrome and stainless steel trim was used more abundantly.
The glove box door has a stainless outer ribbed skin and the upper and lower speaker grille horizontal trim strips are stainless. To create the original look, polish the speaker grille trim plus top and bottom wide glove door ridges to a mirror finish. Paint the speaker grille, ash tray cover, plus the remainder of glove box door interior cab color.
Now comes the detail work. Cut masking tape the width of the valleys between the smaller ridges. Put in position after placing the tape on your pant leg to reduce the sticky surface. You don’t want to take the paint off when you remove the tape later. Next comes the silver paint. This is placed over the small ridge tops on both the speaker grille and glove box door. The result is similar appearing horizontal ridges nicely running between the two dash items just like GM produced them.
Late 1951-1953
These are the years of the Korean War shortages. The glove box door, ash tray cover, and horizontal radio speaker grille trim were stamped from earlier tooling, however, were now changed to painted steel. They are all interior color and there is not even silver paint on the horizontal ridges. Therefore, if you have these years, restoration is easy. Just paint these items cab interior color and your job is done! NOTE: The following image is from a 1953 Suburban which has the red and brown interior. The pickup has the more metallic medium brown interior paint which will be like this Suburban except for the color.
Between 1954 and 1959 the dash cluster of GMC trucks were given a circular opening for a dealer installed clock or tachometer. These trucks left the factory with a blank-out plate to fill this opening. With most GMC’s this plate always remained in place as an option was rarely added.
The enclosed photo shows both plates used during the period. We are requesting help to identify the years each were used. Contact us for your opinion at www.oldchevytrucks.com
On most all early GM trucks their fuel line exited on the bottom of the tank. It was usually attached to a brass shut-off valve which threaded into the tank. In case of fuel pump or line repair, a person had to lay under the truck to turn the tank valve and stop fuel flow.
No doubt, this design resulted in many building fires as the trucks aged. By design, the tank is above the fuel pump. Thus, an un-noticed fuel drip or worse will continue until the tank is drained by gravity. What a dangerous mix in the many homes at that time with basement garages and nearby gas fired water heaters.
In 1954 the needed change occurred. The gas pick-up line now leaves the tank on the top but extends down to almost the bottom. In this way, the gasoline does not drain due to a line leak and sediment stays in the tank bottom.
For the perfectionist wanting his truck authentic, the original system does not have to be a fire hazard. Regularly check the short neoprene flex line between the tank and fuel pump. There is a limit on how long the non-metal flex fuel line can last.
1954 and newer (above)
1953 and older (above)
Among the many updates in the new Advance Design body style in 1947, one that certainly stands out is the change in gas tank positioning. For the first time since 1936 it was placed outside the cab and under the bed.
The dimensions of this 18 gallon tank were based on the limited space between the right frame-rail and the torque tube drive shaft. It was very close to the wood bottom pickup bed and extended at least six inches below the actual frame rail.
GM used this type gas tank in pickups during 1947 and 1948. For assumed reasons explained in an adjacent article on this website, it was placed back in the cab 1949.
This two year tank (It was even a different shape between 1/2 and 3/4 ton trucks) has become very difficult to find in recent years, so it was perfectly reproduced in 2008. Restorers no longer have to accept the high priced “just close” stainless 1/2 ton tank usually accepted by some street rod enthusiasts.
The following photos show close-ups of an original 1/2 ton tank. This may help you be more successful in your hunt for the proper unit among many unmarked tanks at swap meets and older salvage yards. Dimensions are: length 24″, width 12 1/2″, and depth 13″.
Note: This gas tank is the same as the 1/2 ton “Single Unit” body trucks (Suburban, panel, and canopy express) during all the Advance Design years, 1947 through 1955.
Bottom View (above)
Top Left View (above)
Top Right View (above)
Outside View (above)
What’s this bad rap some people give the GM pickups with in-cab gas tanks? For 35 years GM protected these tanks from collisions by double wall reinforced cab metal, doors, and seat frames. The 1937-46 pickups even secured the tank under the seat and surrounded it on three sides by the welded to floor heavy metal seat riser.
If you and your truck are ever involved in a collision so major that the gas tank begins leaking, then imagine what could be occurring if the tank was in most other places on the truck. Unless you have found a narrow tank that fits inside the frame rail and away from the drive shaft, you haven’t located a safer location than what GM used between 1937 and 1972.
For approximately 18 months, beginning with the 1947, Advance Design body style, GM placed their pickup gas tanks under the bed inside the frame rail. This location, while protected from side impacts, was very susceptible to damage from road debris. Leaks from being hit by rocks and stumps soon caused GM to again place the tanks in the cab. Possibly, a protective panel would have given the tank a shield but GM did not use this option. The tank went back in the cab.
In these older trucks you instantly smelled gasoline if the sending unit gasket or gas filler hose began to fail. Trucks with under the bed tanks usually must be parked and dripping before a person smells the vapors.
If you critique the early in-cab GM gas tanks, don’t forget what the manufacturer did to the truck series beginning in 1973. Can you believe? They secured the tank in their pickups to the outside of the frame rail under the bed. The only separation from a broadside accident is the single layered sheet metal bedside! It doesn’t take much of a side impact to flatten the tank with disastrous results.
Currently, the nervous owners of some earlier pickups move the tank out of the cab and place it under the bed behind the rear axle. This new tank position is definitely exposed to major damage from a heavy hit at the rear. An original in-cab tank is nicely protected from most of these rear and side impacts.
Don’t make your truck more dangerous than it was originally!!
An in cab underseat gas tank as used between 1937 -1946…It lays inside a metal seat riser as well as being inside a heavy guage metal cab. (above)
The above photo wa taken of a 1952 Chevrolet 1/2 ton daily driven pickup. The owner was so concerned about the gas tank in the cab that he placed it under the bed behind the rear axle. The non metal tank is just waiting for a rear end hit at about 20 miles per hour. The original bumper will offer little protection and the contents of the tank will spread in all directions…Is this a moving bomb ready to explode?
To help prevent metal to metal contact when 1/2 and 3/4 tons are overloaded or have weak shock absorbers, truck manufacturers used a rubber devise. This cushion prevents the axle from making direct contact with the frame rails.
On the rear of the 1947-1953 GM pickups, it attaches directly to the underside of the hump in the frame. It is not meant to be removed during the life of the truck.
In 1954 a change in the overload bumper location was necessary. This was the first year for a redesigned step bed which was three inches deeper. To keep the top edge of this new bed the same as earlier years, the hump in the frame was lowered. It was necessary to place a bracket on the side of the frame rail and add this bumper. The attached photo shows this repositioning of the overload bumper.
1947-1953 (above)
1954-1955 (above)
These are some very rare photos. It is quite unusual to find 1947-1953 Chevrolet and GMC 1/2 ton bare frames together. Here, you can cmpare the differences in the front cross members.
As the GMC six cylinder is a few inches longer than the Chevrolet, engineers designed two different front engine cross members. In building the truck frame for the assembly line a different cross member was added depending if it was to be in a Chevrolet or GMC factory.
This is why re-builders of GM trucks today develop immediate problems when they exchange 6 cylinder engines between the Chevrolet and GMC. The two makes may look about the same in any year, however the power plant causes changes not only in the frame’s front cross members as well as sheet metal in this immediate area.
Photos courtesy of Rob English
Email: rob@oldgmctrucks.com
Website: Oldgmctrucks.com
During the Advance Design years no less than four different Chevrolet hood side emblems were used on 1/2 tons. Each of their two mounting pins are in the same place so the punched hood holes were unchanged during these years. All were chromed die cast even during the 1952-1953 Korean war chrome shortage.
The following pictures show the correct emblem for each of the years. Beware, some vendor’s catalogs do not list them correctly.
Note: Between mid-1949 through 1951, a separate small 3100 emblem was placed below the Chevrolet letter plate. Therefore, hoods during these years will have two additional factory punched holes. The longer Chevrolet emblem used between 1949-1952 are the same.
1949-1951 3100 Emblem (above)
1955 First Series (above)
1952 (above)
1953-1954 (above)
1947-1949 Thriftmaster (above)
As with many other items on the Advance Design Series trucks, there were also changes in the ignition switches. Both Chevrolet and GMC shared there several switch changes during the sever year series.
In the beginning (1947-1948) a unique three position ignition cylinder and housing was introduced. This was a first for GM trucks. It related to a country with limited crime and a time when many people did not lock their houses. The switch allowed the truck to be started without a key.
By turning the cylinder and key to the far left, the ignition switch was locked. However, the middle position was the big difference! Here the ignition was still off but a small tab or teardrop extending down from the cylinder face allowed the driver an option. With a touch of a finger you could turn the cylinder to the far right with or without a key due to the teardrop.
This was a convenient feature for many owners, particularly on the farm. No longer did they worry about losing the key or having to dig when it was in a pocket. They simply moved the tab from the center to the far right and the ignition was on. A security feature was built in. The ignition could not be locked without the key, so there was no worry about it accidentally being moved to the lock position.
This three position switch, also used on the 1947 Chevrolet car, was discontinued about the end of 1950. GM then returned to the two position on-off cylinder and housing that would not work without a key.
Between 1947-1953 the switch and cylinder combination plus a one candle power bulb and socket was attached to a sheet metal housing. This assembly is screwed to the top of the lower dash lip out of sight. Only the round key cylinder face is seen by the driver. It extends through a larger hole in the dash. A resulting 1-1/16 inch circle opening between the dash and this cylinder face produces a lighted ring at night from the adjacent small bulb. This allows the driver to easily locate the switch in the dark.
In 1954, with the total redesigned dash, there was a complete change in the ignition switch. The threaded end of a die cast housing is held in the dash by a chrome lock ring. Only this ring and the key cylinder face is visible to the passengers. It is also the two position on-off type.
With the introduction of hydramatic transmission during these years the switches did not change. The starter motor was activated by a button near the headlight switch not by the ignition switch.
1954 Ignition Switch (above)
1954 Ignition Switch Rear View (above)
Both Chevrolet and GMC used the same steering wheel during the 1947-1953 Advance Design years. To keep the two makes just a little different the horn buttons had a separate design. Thus, the driver was always given a close view of the name of the truck he was driving.
Chevrolet: Horn cap is chrome and then painted with steering wheel color. The raised Chevrolet letters and surrounding ridges are free of the paint so the chrome is visible (above)
Horn cap painted to match the steering wheel with red lettering. No chrome. (above)
During the 1947-1955 years, no less than four different front hood emblems were used during regular production on the Chevrolet 3000 series trucks. Though all can be made to interchange during this 7 1/2 year series; for the perfectionist, there are only certain types for certain years.
In 1947, the 1/2, 3/4, and 1 ton Chevrolet trucks began production by displaying a chrome plated die cast emblem with dimensions of 3-3/8″ x 19″. The Chevrolet letters across the center are red and a small royal blue “BOWTIE” is above. On the back side their four attaching points (part of the casting) are threaded and extend outward to better provide metal to hold the securing screws. Because of the length of these four extensions, the hood must be provided with appropriate dimples. These dimples are necessary so the emblem can be pulled snug against the hood front.
Sometime in late 1948 and early 1949, depending on the assembly plant, this emblem changed to chrome plated stamped steel. Visually, it has the same dimensions and painting as the earlier style but is much less in weight.
In late 1952, the front of this emblem was again changed. It was now stainless steel. The four hood attaching clips (welded to the front stainless) and the threaded studs remained plain steel as in the prior style. The dimensions were as in past years. This design was carried through all of 1953. Forty five years later this stainless steel emblem is often seen at flea markets with the front skin in excellent condition but the four welded-in clips either gone or rusted beyond repair. These clips, hidden between the stainless emblem skin and the hood front, did not dry quickly between rains and the morning dew.
Because the hoods are larger on the 4000 and 6000 series 1-1/2 and 2 top Chevrolet trucks, the front emblem was formed to conform to their bigger size. Width and length dimensions are the same as the smaller 3000 series trucks and will interchange. However, to help compensate for the larger hood size, these big truck emblems are almost 1/4″ thicker at their widest point in comparison to the smaller 3000 series. Their construction materials changed during this series as did the smaller 3000 series trucks.
The 5000 series Chevrolet COE bodies (CAB OVER ENGINE) did not change their initial die cast hood emblem. It continued identical from it’s 1947 introduction through 1953. The dimensions 3-1/2″ x 26-1/2″ were much longer than the conventional cabs due to the COE’s massive one piece hood.
The 1954-1955 hood emblem was a different design and better related with the totally new grille. As Chevrolet was now stamped on the top grille bar, these letters were no longer on the emblem. The “BOWTIE” trademark became larger and the overall emblem continued with a stainless skin and plain steel inside attachments overall dimensions on the 3000 series trucks is 3-7/8″ x 21″. With this new design, the clips did not extend back as in prior years. Therefore, the dimples were not stamped in the hood. This is a quick way to tell the 1954-1955 from the earlier 1947-1953 hoods.
On the 4000 and 6000 series the 1954-55 Chevrolet emblem has an overall increase in size of approximately 20% or 4-1/8″ x 24″. This was necessary to better conform with the larger truck hood. The emblem remained a stainless steel stamping with the same appearance as the smaller trucks.
General Motors designed the 5000 series or COE emblems on the 1954-55 the same in size and style as those on the conventional cab large truck hoods with two exceptions. This COE emblem is chrome plated die cast and lacks the notches for the bullnose strip. The unique one piece size of the COE hood eliminated the need for a center divider strip and thus no center notches were in the emblem.
Early 1955 COE
All the truck “BOWTIE” emblems in 1954-1955 were Chevrolet royal blue however the valleys between the twenty four vertical ridges were painted red in 1954 and white on the early 1955 series. The GMC trucks between 1947-55 did not have a front hood emblem. Die cast GMC letters were attached to an upper grille housing.
Hood ornaments were an important part of automotive styling in the 1940′s through 50′s. However, as trucks were basically for work GM created specific ornaments for these vehicles but made them a dealer accessory. They are rare and in demand today as hobbyists now look for General Motors accessories to add to their restored trucks.
To help the dealer install the 1947-1953 Chevrolet accessory ornament correctly, the factory placed a small hole between the hood halves 33″ from their rear edge. This is for positioning the rear threaded stud of the ornament. The dealer would then drill two pair of holes on either side of the hood divider strip and the result was a perfect fit.
On the 1954-1955 Chevrolets, the accessory ornament was totally changed in design. A chrome eagle with low wings was attached to a die cast base. To save expenses GM used the same eagle that was also an accessory on 1953-54 Chevrolet passenger cars. The mounting base was not the same partially due to the difference in the width of car and truck hood bullnose strips. Between 1947-55, the dealer installed GMC accessory hood ornament did not change. It had a very narrow die cast mounting base attaching directly to the bullnose strip. This supports an attractive streamlined jet plane. It does not resemble the Chevrolet ornament.
As time progressed, GM realized their under floor battery position needed extra protection. The battery on the 1946 and older trucks were only protected by their partial tray. No doubt some hard working vehicles in rural areas lost their battery from fractures.
Thus, the 1947-1955 trucks were provided with a front vertical metal shield. The attached photos (coming soon) show a bare frame with this shield still in place.
These chrome hood ornaments were exclusively tooled for GMC trucks and have no similarity to the Chevrolet style. They are made up of three attached die cast pieces to create the finished product. Their slim base secures to the center of the hood divider strip.
These were dealer installed GMC accessories. As trucks at that time were mostly for work responsibilities, few owners had an interest in appearance options. Thus, these hood ornaments were rarely seen on trucks when new. Locating new or restorable unit 50 years later is almost an impossibility
In 1953 Chevrolet/GMC trucks adopted the more modern relay activated horn. To keep cost low, GM used the same seashell type horn that had been on Chevrolet cars since 1949. It displays the number “689″ in its die cast metal. In the Chevrolet Master Parts Catalog, the number when ordering a replacement was 199687.
Though the 1953 truck used the existing car horn, GM created a special right angle bracket to attach it to the small extension on the iron intake manifold. This bracket has become very rare today. Most people incorrectly think the 1952 and older horn should attach to a 1953.
1952 and older horn position (above)
By 1954, the Korean War shortages were history. More trim and chrome plating began to show up in trucks and cars. The Chevrolet and GMC truck divisions both introduced a deluxe model for their pickups during mid-year 1954. Hopes were to appeal to the emerging buyers with more disposable income.
The deluxe model of these two trucks shared most of the same sheet metal, however special unique items kept each individual! One of these exclusive items was used only on the top of the line GMC pickup. This was the bed-roll reflector. It was never placed on Chevrolets or the basic GMC pickup.
In today’s world this extra is almost impossible to locate. Not only was it on the deluxe GMC’s but few of these top of the line models found buyers. Most still thought of trucks as workers and ordered the basic vehicle. This reflector is on the very end of the bed roll and it is exposed to being damaged while backing.
To save tooling costs, GMC designers borrowed the red reflector lens from the 1953 Buick taillight. Unfortunately, the stainless ring (riveted to the bed roll) is exclusive only to the rare deluxe GMC pickup.
It’s 1954 and the Korean War is now history. The wholesale price of non-ferrous metal such as chrome, stainless steel, nickel and copper are dropping. American have more disposable income and are beginning to ask for deluxe accessories on their trucks instead of just for the family sedan.
Of the many accessories introduced in 1954, the full wheel cover was a first for any Chevrolet pickup. These stainless steel covers were not borrowed from Chevrolet cars. They were exclusive for the 1/2 ton pickup 16′ wheel. These were Chevrolet dealer installed accessories and not added on the assembly line.
Today, locating a restorable set of these unusual accessories is very difficult. Many sets that were left over in dealer stock probably found their way to the used car lot to dress up a trade in.
Note: Don’t confuse these covers with the 1947-48 Chevrolet car, deluxe 16′ wheel covers. They have red centers and a different stamping in this area.
The horn location on the intake manifold of the Chevrolet 216 six cylinder changed position with the addition of the accessory oil filter. This oil filter was attached to the front of the intake manifold. A special shaped horn bracket was necessary to move the horn forward away from the filter. This bracket was included in the box with the new oil filter package.
From 1947 and older, even the 3 speed transmissions shifted on the floor. There was no column shift. Without a shift box on the steering column, the oil filter could be placed on the rear of the intake manifold. Thus, the moving of the horn forward does not apply during these early years.
The attached photos show the two styles of horn brackets used between 1948 and 1953. On 1954 and newer the horn is attached to the radiator support.
In the 1953 Chevrolet truck accessory book, there is a charging bull head displayed as an optional hood ornament. During my past 20 plus years in this hobby, I have heard reference toward this accessory but have never seen an example or heard of another person seeing one. Does a reader have one? Has anyone seen this option on an original truck? Did this ornament actually make production after the 1953 booklet was printed in late 1952?
Accessory Hood Ornament
During the Advance Design years, 1947-55, Chevrolet and GMC each changed their grill designs twice. GMC made the change at the end of the second year and Chevrolet made the change at the end of the seventh year.
Possibly to save tooling cost GMC, not Chevrolet, always used the same grill on all truck sizes in any one year. As Chevy used a similar but slightly larger grill on their 1 1/2 and 2 ton. GMC did not change the size on trucks between 1/2 and 2 tons.
In 1947-48 GMC used a three bar heavy gauge chrome steel grill. Actually, it was for the heavy weight for the 2 tons but fit in the 1/2 ton by using a smaller grill surround.
The big grill change for GMC was in 1949 when it was made as a four bar design. To the non truck enthusiast, it looked somewhat like the earlier years which is probably what GMC designers planned.
Current GMC grill reproductions are often sold as 1947=55. Actually they are the four bar type for 1949-55. The 1947-48 GMC owners get a surprise due to the modifications needed to fit the later reproduction grill into their early housing!
Click on images below to enlarge
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| 1947-1948 Three Bar Grill | 1947-1948 Three Bar Grill | C.O.E Four Bar Grill |
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Three to Five Ton Four Bar Grill
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Half Ton to One Ton Four Bar Grill
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Half Ton to One Ton Four Bar Grill
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One of the more common reasons for slow engine turnover using an original six volt system is under size battery cables. Most of today’s auto parts stores only stock the smaller diameter 12 volt design. Unknowing owners mistakenly replace their original worn cables with shinny new ones that are as much as half the diameter as needed. Two ground cables are also required: One from the battery to the frame and one from a starter mounting bolt to the frame.
Six volt starters require twice the electrical flow to operate properly. Don’t blame your six volt system for slow unacceptable starter motor speed! Many restorers go to the expense of changing their 6 volt system to 12 volts. They feel their original system was inferior and believe what they did was necessary. The problem could have been corrected with just adding the three proper cables.
Remember: Millions of cars and trucks were made with 6 volt electrical systems each year. If they had not operated correctly they would have been built with 12 volt systems!
Between 1947-1953 the Chevrolet 1/2, 3/4, and 1 ton grills were made from the same tooling. However, the paint colors and some with chrome plating made a difference. For the perfectionist, the following data will help you build a correct grill during your restoration.
The standard grill has inner and outer bars the body color. Horizontally, a pin stripe is run on the edge of the five outer bars. It is the same color as the cab stripe.
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Standard grills have outer bars the body color without a horizontal stripe. The inner back splash bars are white.
Outer bars on standard grills are the body color as prior years. The back splash color changes to Thistle Gray (light gray) to match the newly introduced gray hub caps and bumpers.
The deluxe grill has the five outer bars in chrome. The four inner bars remain the cab color.
The chrome grills for these years are plated on the outer bars. The back splash color remains the same white as the painted grill.
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No chrome grills produced due to the Korean War shortages. The grills are the same colors as the standard trucks.
The two outer vertical bars touch the fenders and are therefore this color. Unfortunately, the reproduction grilles are easily recognized at shows because the owners have not painted their outer bars fender color! The three inner vertical bars are semi-flat black. This prevents them from being easily seen when viewing the vehicle.
Used only the first 1 1/2 years into this body style, these GMC grilles stand out for their different shape and very heavy duty construction. Because of it’s weight this assembly, it sets on the frame and is given extra support by a pair of steel rods extended at an angle to the frame rail. See photo.
The grille has three horizontal bars and uses a heavier gauge metal than the four bar grille introduced in 1949. This same unit is found during 1947 and 1948 in all 1/2 ton through 2 ton GMC trucks.
On these early 1/2, 3/4, and 1 ton trucks the splash apron from the grill to the bumper is even different. The front bumper is the most unusual. It is rounded much like an automobile and has three bumper bolts on each side. They all have the small grill guard on the 1/2 and 3/4 ton.
Some suppliers of 1947 – Early 1955 bumpers and grilles state they are all the same. But, they are not. The 1947-1948 stands alone!
1947-1948 “3″ Bar (above)
Note the 3 bumper bolts. The center secures the front splash apron and securing braces. The other two are used by the dealers to attach GMC accessory larger grille guards to the bumper.
1947-1948 “3″ Bar (above)
1947-1948 Angle Grille Support (above)
1949-1955 “4″ Bar (above)
Many of the tech articles on this web site emphasis’s the subtle ways that truck parts were made economically by GM. Truck often received Chevrolet car items that were used the year before. Sometimes even other GM brands sent their older items to be placed on assembly line trucks.
Of all the ways GM saved money on truck parts, none is more unique than the savings on 1/2 ton hub caps. Chevrolet pickups used the same baby moon style hub cap from 1940 through 1955. The skins and basis are the same. A relative inexpensive addition was simply changing the lettering or emblems on the outer brass skin. They required a change in tooling, not expensive for a company the size of the Chevrolet Motor Division. The stamping department just kept making the same base and skins. The skin surface stamping changed as was required by the design department each year.
Check the following pictures. The base hub caps are all the same. Some of the car hub caps are the same as the trucks. Even GMC trucks decided to use these caps between 1947-55. After all, just placing the three GMC letters on the skin added much savings to the company’s bottom line.
1940 Chevrolet 1/2, 3/4 ton and car (above)
1941-1946 1/2 ton, 1941- 1945 3/4 ton, and 1942 -1948 car (above)
1947-1951 GMC, Chrome (above)
1947-1951 Chevrolet, Chrome (above)
1954-1955 1st Chevrolet (above)
1952-1953 Chevrolet Painted (above)
Installing the door weather seal on 1947-1955 G.M. trucks is not difficult, however some extra knowledge is required. Gluing it to the door edge incorrectly will limit it’s ability to seal drafts and add to wind noise. It is just as easy to attach this seal correctly.
The design of correct weather seal is square on the bottom that holds the glue. On the opposite end are two ears, each being a different length. The short ear is glued against the door and does not extend beyond the door edge. It should not be seen when the door is closed. The longer ear receives no glue and extends further up to touch more of the cab or body when the door is shut.
A nice touch at the two lower corners is to cut these ends at 45 degrees. The horizontal rubber bottom can be turned over so the metal lower windlace retainer fits in the groove between the two ears. It is a package that all looks very nice once placed together.
A view of the 45 degree angle where the side and horizontal bottom door weather seals join (above)
Here, the weather seal is installed on the door incorrectly. Note that the long ear can not reach the door post or body. (above)
This photo shows an incorrectly installed door weather seal. Note the long ear is visible when the door is closed. Not correct.(above)
Short ear side, glued against door | Longer side, mounted away from door (above)
The placement of rear axle bumpers by GM on 1/2 tons proved to be an important feature. Owners can often load cargo over recommended weights, their shock absorbers may lose their resistance, and there is the existence of uneven road surfaces. All this can make axle bumpers very important.
During the hauling of freight, these bumpers occasionally stop metal to metal contact between the frame rails and the axle housing. GM placed them just above the rear axle.
See photos.
1947-1953 1/2 ton (above)
In 1954 GM increased the depth of the 1/2 ton pickup bed from 15″ to 18″. To do this they lowered the frame rail arch above the rear axle. This shortage of space caused the bumper to be placed at the side of the frame but still above the axle.
1954 1/2 ton (above)
Leaf spring width on 1/2 ton pickups remained at 1 3/4 inches until the introduction of the two inch width on the Task Force 1/2 tons in mid 1955. The early narrow springs worked well considering the engine horsepower and weight limitations of the 1/2 tons. The two inch springs became standard equipment on the rear of the 3/4 ton in 1946 but their fronts still remained the smaller size. This is because the increased weight carrying ability of the 3/4 ton is mostly felt in the rear. Only 1 ton and heavier were totally without the 1 3/4 inch springs.
With the abuse given pickups in the early days (poor roads, overloading, and almost no lubrication), the springs have held up well. Most mid 1955 and older 1/2 tons continue to operate with their tired original narrow springs.
In today’s world a new variable exists that puts even more demands on these small springs. It is the increased horsepower of later model engines. No problem if these trucks, converted to more powerful engines, are driven as if they still have their original six cylinder. However, problems arise with jack rabbit starts with or with a heavy freight load. Most of these Advance Design 1/2 ton’s with transplanted V-8′s have had their original closed drive shafts replaced with open systems. The replacement axle housings are clamped to the 1 3/4 inch rear springs. When heavy acceleration is forced on these modified trucks, the axle housings try to rotate due to the extra torque. Much of this movement is held in check by these narrow springs. They just weren’t designed for this. Breakage and permanent bending can occur.
Don’t push your 1 3/4 inch rear leaf springs beyond their limits. If you demand fast acceleration with your V-8 1/2 ton, convert to later model 2″ or 2 1/2″ springs. Check specialized suppliers, including Jim Carters Truck Parts (part # HP580), for add-on kits.
The straight axle ½ ton GM pickups (1959 and older) were built tough! They served their purpose as the best in work vehicles for over 30 years. Other than an occasional kingpin replacement, they were almost ‘bullet proof’.
In today’s world, the reasons for owning an older truck, has generally changed. Most have been retired from work responsibilities and have become ‘fun trucks’ driven with care on smooth streets. Hauling merchandise is far down the list of their use.
The resulting demand for a smoother ride and better braking is the reason for many suspension options available from supply houses. For those willing to compromise on originality for an easier ride, one of the most proven and less expensive upgrades is the front suspension of the AMC Pacer. The price is right and the results are excellent. This coil spring rack and pinion front suspension assembly gives passenger steering and ride qualities.
A specialized adapter plate (available from the catalog on this web site, HP127) allows for the connection to your ½ ton truck. Instructions explain parts to remove from the Pacer assembly before the plate is welded in place. The total assembly is then bolted to the truck front cross member. No cutting on your truck! You can even trim the Pacer coil springs to get a lowered level on the total vehicle.
The adapter plate is not expensive. The main project is locating a good Pacer front suspension. This AMC vehicle was produced between 1975 and about 1982. The later years even had disc brakes.
AMC Pacer (above)
1947-1953 Advance Design (above)
Trucks of the early years were often exposed to the rough terrain of local gravel roads as well as the dirt ruts on the farm. Quality, long life shock absorbers were a necessity. Therefore, trucks from the mid 1930′s through 1949 continued with a proven design carried over from earlier vehicles.
The highly successful lever action shocks had been used since the 1930′s on GM cars and trucks. They should not be confused with knee action shocks on the front of mid 1930′s Chevrolet passenger cars. This is a totally different system.
Lever action shocks are simple in design but excellent in quality and long life. Their cast iron fist sized housing, bolted to the frame rail, contains hydraulic fluid and basic internal parts. The fluid is forced through a small internal orifice as the vehicle encounters uneven road surfaces. The slowness of the moving liquid inside the shock gives a cushion action that softens the ride.
The workmanship built into these lever action shocks are an excellent example of quality GM engineering. On many trucks throughout the country these factory shocks are continuing to serve after 50 years and with the abuse of no past servicing.
The weak point is the small rubber bushings at each end of the link, not the actual shock assembly. During many restorations the hydraulic fluid is changed, link bushings replaced, and the shock continues to operate like new.
Single action shock absorbers were standard equipment of the 1/2 ton and 3/4 ton trucks with an optional double action type available for more heavy duty requirements. A single action design has resistance only on the upward direction of the wheel while a double action style slows wheel movement on rough roads in both directions.
Basically the horizontal arm extending from the shock housing is attached to a vertical link that extends upward from the axle. The movement of the tire then causes this link and shock arm to also move, thus forcing of hydraulic fluid between chambers inside the shock housing giving a cushioning to road bumps.
In 1950, the lever action units were discontinued and replaced on new trucks with a modern tube type sheet metal shock. (This design continues to be used on today’s vehicles.) It should be strongly emphasized, the lever action shock absorber was not discontinued because it was inferior, but rather because the new style cost much less to produce and install. It was simply a matter of economics. The fact that lever action shocks had the potential to last 50 years over the 3 to 4 years of the modern unit did not prevent the change over!
During all of the 1947-1955 series, the five window cab, often referred to as the Deluxe cab, was available as an extra cost option. Their two corner windows helped in visibility especially when backing. Cabs made during the same year are identical except for these corner window options. Some buyers in the southern states rejected this option. They felt these corner windows made the cab interior much hotter during the summer months.
Beginning in 1953, tinted windows became a factory option. Though today’s glass shops can easily cut and add the replacement flat tinted windows. However, the optional curved tinted corner windows are not easy to locate. They were only available from the factory between 1953-1955. The few originals are usually scrapped and pitted.
In the last few years a replacement corner window has been reproduced. They are available in green or gray tint. They are kept at Jim Carters Truck Parts as well as other full stocking dealers.
With the increased popularity of the Advance Design Suburbans (1947-1955), questions are often asked in regards to the proper seat arrangement. This eight passenger vehicle was the only GM “people hauler” on a truck chassis and still remains a popular carrier for the family.
This body style was only produced on a 1/2 ton 116″ wheelbase chassis (the same as a pickup except for 4 riveted right angle brackets to better support the body). The extra weight capacity and stiff ride of a 3/4 ton was not necessary for a vehicle carrying passengers and expected to do almost no towing.
Two seats at front consist of a 3/4 unit for the driver which can be adjusted several inches front and back. The far right non-adjusting jump seat is designed to tip forward and allow passenger access to the rear seats.
The middle unit is also only the 3/4 size. It has the same size cushions that are used by the driver, however, the framework does not adjust. It must be this 3/4 width to give room for passengers to reach the rear seat.
This back seat has full length “crowded” three passenger cushions. In today’s world, it is the rarest seat! Though all Suburbans originally had this back seat, many were removed to give more loading capacity for merchandise. They were probably put in storage or used as a seat in the barn and then forgotten years later when the Suburban was sold to the second owner.
During rebuilding of the Advance Design cab, the hobbyist will observe remnants of a tar paper material secured to the underside of the roof. This was partially for insulation but even more as a noise retardant. This reduces the bell sound in the cab when driving or slamming the doors.
When restoring your truck, be sure to replace or improve this material under the roof. Tar paper secured with layers of home roofing cement works well. It is not visible once the headliner is in place and will add to the quietness of the cab.
Yes, rubber pedal pads from 1947 through 1959 look the same when installed. However, because of the design of the metal pedal below them, they are different on their backside. Some suppliers market them as one item but the attached pictures will show this as not true.
Same Outer Surface (above)
1955-1959 Left | 1947-1955 Right (above)
Over the years we have been asked ‘Where can we locate the chassis frame for a Suburban or panel truck?’ The answer is not complicated. To save much money General Motors used a modified frame from a pickup. The difference is four right angle brackets riveted to the frame. These provide an attaching point for the large single unit body (Suburban and panel truck).
On most pickups, these frame holes are even punched at the factory so the long side rails can be used for either body style. Therefore, if your Suburban or panel truck needs a frame, your hunt will be less difficult. The attached photos show body mount brackets on a 1954 as they were installed at the factory.
The very practical panel truck produced from the early 1920′s through 1970 was an excellent cargo vehicle. Merchandise was protected from the weather and equally important from easy theft. Being a freight hauler, its cargo floor is like the pickup truck. Hard yellow pine and cross sills support the weight and merchandise slides on the metal strips.
Though not obvious, a major floor design occurred in the 1/2 ton panel truck in 1950 of the Advance Design years. Prior to this, the floor consisted of about six wood panels, each separated by 1/4″. Covering this gap was the necessary 1 1/2″ wide metal bed strips. To prevent dust from coming through the wood plank separations, GM changed the bed to a single piece of 3/4″ marine plywood in 1950. It appears this was the same size that was used with the flat floor board Suburban. However, with the panel truck the plywood was grooved for the bed strips. Once installed in the truck it looked like strips between the earlier individual planks.
With the change in the bed floor, the length of the strips were reduced from 82′ to 79 1/2″ at least thee of the punched holes in the early and late strips are in a different position.
1947-1950 1/2 Ton Deluxe Panel (above)
1947-1950 1 Ton Deluxe Panel (above)
Beginning in 1950, GM introduced an improvement in the cargo area of the panel truck and Canopy Express. It now followed the example of the Suburban by using a one piece, 5 ply floor. This replaced the planks that were always used in the pickup.
GM implied this would better seal dirt and dust from an otherwise closed area used to haul merchandise and food products.
The following data and picture is as removed from a 1950 pamphlet announcing new features for that year.
