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'71 GMC

Posted in Project Vehicles on August 1, 2000 Comment (0)
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'71 GMC
Photographers: John Cappa
p169392 large+1971 GMC+Front Driver Side
p169393 large+1971 GMC+Rear Axle
p169394 large+1971 GMC+Truck Bed
p169395 large+1971 GMC+Engine
Lots of body modifications were performed and one of them was trimming the rocker panels and replacing them with rock sliders. If you have ever driven a fullsize in the rocks then you know the usefulness of this modification. Lots of body modifications were performed and one of them was trimming the rocker panels and replacing them with rock sliders. If you have ever driven a fullsize in the rocks then you know the usefulness of this modification.
For the rear discs, Brian fabbed a 3-inch spacer onto which a 1/2-ton caliper bracket was welded. It bolts to the 14-bolt axletube. The 14-bolt spindle was retained, but the hub was redrilled to match the six-lug pattern of the 1/2-ton rotors. Custom Moser shafts finish it off. For the rear discs, Brian fabbed a 3-inch spacer onto which a 1/2-ton caliper bracket was welded. It bolts to the 14-bolt axletube. The 14-bolt spindle was retained, but the hub was redrilled to match the six-lug pattern of the 1/2-ton rotors. Custom Moser shafts finish it off.
Things get interesting when it comes to the rear axle. It uses a 12-bolt center section with fully-gusseted 14-bolt tubes. Brian took three days to set up the 4.88 gears and Detroit Locker himself. Things get interesting when it comes to the rear axle. It uses a 12-bolt center section with fully-gusseted 14-bolt tubes. Brian took three days to set up the 4.88 gears and Detroit Locker himself.
p169399 large+1971 GMC+Rear View

For some reason we just drool all over ourselves when we see a ’67-’72 Chevy pickup or Blazer. Something about the raw lines of the truck just screams that it is a truck. They evoke the days when trucks were actually trucks and had the aerodynamics of a barn door, got the gas mileage of a tank, and had the drivetrain of a semi-truck. They erase from our minds the modern-day phrases “car-like handling,” “a lower step in height,” and “quietest interior ever.” So it was no wonder we scrambled across the slickrock of Moab, Utah, at breakneck speed to catch up to Brian Thomas of Taylorsville, Utah, and his ’71 GMC.

After catching up to Brian and wiping the drool off of ourselves, we were giddy with glee to find out that his rig was much more than just a lifted and locked classic. Lots of folks who own fullsize trucks throw a lift on, stuff in a couple of lockers, and mount some bigger meats, and then call it done. We gladly listened to Brian’s lecture on all the tinkering and tweaking he had done to his ’71.

The modifications first began with the suspension. A combination of Skyjacker, Trail Master, and Tough Country parts was used to net 6 inches of lift. The Chevy’s body was pushed another 2 inches skyward with a body lift. Then Rancho RS 9000s were mounted on each corner to provide a smooth and adjustable ride. With the new gain in altitude, 38-inch Super Swampers on 15x12 Eagle alloys fit just fine without any rubbing.

OK, now the modifications really began. Brian busted out the thinking cap and began work on the rear axle. The 12-bolt centersection was mated to 14-bolt tubes that netted the full float design of the 14-bolt without losing ground clearance. Then front GM calipers, rotors, and brackets were grafted into position. The axle was also widened 3 inches to match the front. Finally, a Detroit Locker and 4.88 gears were stuffed into the rear pumpkin. A Dana 44 was ripped out of a ’75 Chevy and slung into position under the older iron. It was trussed and gusseted for strength. After all that, 4.88 gears were used to turn the 38s, while an ARB Air Locker supplies the traction. Both axles were assembled in the basement and carried out to the truck when completed.

To provide motivation for the heavy steel, Brian yanked a Chevy 350 out of a stock car he had built. It was bored 0.060 over and the compression was bumped to 10:1 to make some horses. An Edelbrock RPM Air Gap intake manifold drinks fuel from an 850-cfm Quadrajet. A GM HEI then ignites the mixture which, after being destroyed, escapes through Hooker headers.

Backing up the 350 is an SM465 four-speed transmission taken from a mid-70s Chevy along with all the necessary bracketry. The venerable NP205 transfer case was used to finish off the stout drivetrain. Custom-made driveshafts then send power to the axles. Next, a little love was shown to the body. In one of the more interesting modifications, the longbed was shortened 18 inches, which allowed Brian to keep the wheelbase but get rid of the overhang. The rockers were cut out of the truck and rock sliders were fabricated and put in their place. Some slight fender trimming was performed and then Brian welded in his own steel flares. After acquiring some surplus paint, the ’71 was bathed in olive drab and black to give it a military look.

Hopefully Brian’s truck will serve as proof that fullsize guys are finally waking up and building their rigs to perform well on the rocks and not just in the mud.

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