My fascination with GMC pickups started when I was a teenager. My cousin’s vehicle to drive was a ’56 GMC 100 with a 316 Pontiac engine. So, many years later when I could afford to build a truck I found one at a car show for sale. After a few years, I finally got started on it. A good friend of mine was a body man all of his life and had a business he left to his son. I made a deal with his son: if he helped me with the body work on the GMC I would help him with the mechanical work on a Cobra kit car that he had. In a year’s time, we did a frame off restoration including a Heidts independent front end (with disc brakes and rack and pinion steering), and a 4-link system in the rear. We used a ’64 Catalina differential with 3:42 gear and a posi unit.
The engine was a 316 cid and has the same bellhousing pattern as Pontiac motors up to the 1960s. I used a ‘65 389 and bored it out to 4.092 and installed a 4” stroke crankshaft. This combo made it a 428 engine and it bolted to the ’56 original bellhousing. From an earlier project, I had ’64 GTO heads and a Micky Thompson Cross Ram intake with (2) 750 cfm Holley carbs. We used flat tappet hydraulic lifters, Lunati camshaft (.468 x .480 lift at 220:233 duration at .050). The A/C we installed was an old air unit from a 2nd series GM pickup. I used a Griffin aluminum radiator.
My wife insisted that I reuse the column shift (3-speed shift) so that’s what I did, except we made it a 4-speed shift and 4th gear being overdrive. When reverse is needed, we pull the column shifter in neutral and pull out a Tee-handle overdrive cable that shifts the trans into reverse.
The truck was a small back window model when we got it, so that had to go. The after market people make the whole back of the cab in two pieces, inner and outer to change to the wrap around rear glass, We cut through the back of the old cab from drip rail to floor pan and the rear door part, then welded in the new panels.
We painted the truck Tropical Turquoise which was used a lot in 1957 and Artic White through the middle.
We had the body all done painted, down to the frame and we were ready to install the rear window. It wouldn’t fit. We ruined two rubber seals trying to make it go in. The glass is tempered and cannot be sanded. The only option was to make the hole bigger! I cut two 2x4s that were about 18” long and put a groove in the 4” side of the 2x4. I put one on top and one on the bottom. I stuck a porta-power between and jacked the hole 3/16” bigger. That allowed the glass to go in.
We used all new repo parts on the bed with pine flooring and all of the fasteners are stainless steel. To hold up the tailgate, we eliminated the chains and used nylon straps with spring loading sliding latches on both sides.
We used Auto Meter gauges in the dash and mounted the fuel tank under the bed behind the rear axle. We now fill the tank in the bed floor.
Story by: Tom Wilhite; photo by Paul Bergstrom
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