• JP Magazine
  • Dirt Sports + Off-Road
  • 4-Wheel & Off-Road
  • Four Wheeler

'91 GMC

Posted in Project Vehicles on May 1, 2000 Comment (0)
Share this
Photographers: John Cappa
p92300 large+1991 GMC+Front Passenger Side
p92301 large+1991 GMC+Passenger Side
The 502 engine is topped by a Holley 850 double-pumper. Underhood highlights include an MSD ignition, custom headers with 2-inch primaries, an aluminum radiator, and a tube frame. The 502 engine is topped by a Holley 850 double-pumper. Underhood highlights include an MSD ignition, custom headers with 2-inch primaries, an aluminum radiator, and a tube frame.
The interior is dirt-simple, with Corbeau seats and a 26-point cage. A gauge cluster sits above the engine tunnel, and the hydraulic steering is actuated via a removable custom steering wheel. The interior is dirt-simple, with Corbeau seats and a 26-point cage. A gauge cluster sits above the engine tunnel, and the hydraulic steering is actuated via a removable custom steering wheel.
First Engineering built the Power-Locked Dana 60 with 4.56s, as well as the four-link and sway bar. The Freightliner hydraulic steering cylinder could probably bend solid steel if given the chance. First Engineering built the Power-Locked Dana 60 with 4.56s, as well as the four-link and sway bar. The Freightliner hydraulic steering cylinder could probably bend solid steel if given the chance.
A massive 14-bolt with custom bracing holds a Detroit and 4.56 gears. Braided lines ensure the brakes are properly juiced in the event of an aborted takeoff. A massive 14-bolt with custom bracing holds a Detroit and 4.56 gears. Braided lines ensure the brakes are properly juiced in the event of an aborted takeoff.
The NP205, as identified by the round plate with three bolts, is a divorced unit out of a ’76 Suburban and sits on a custom crossmember, as does the TH400 transmission. The NP205, as identified by the round plate with three bolts, is a divorced unit out of a ’76 Suburban and sits on a custom crossmember, as does the TH400 transmission.
The front four-link uses rod ends at all mounting points. In the event of U-joint failure, both 76-inch driveshafts are kept on-board by custom driveshaft loops. The front four-link uses rod ends at all mounting points. In the event of U-joint failure, both 76-inch driveshafts are kept on-board by custom driveshaft loops.
The rear four-link employs massive lower arms and mild-steel tubing to locate the axle. The 502 puts out 567 lb-ft of torque, necessitating the antiwrap bars on the lower links. The rear four-link employs massive lower arms and mild-steel tubing to locate the axle. The 502 puts out 567 lb-ft of torque, necessitating the antiwrap bars on the lower links.
The 38.5x16.5 Swampers on 9.75x16.5-inch Alcoas don’t rub anywhere, despite tons of axle travel. Bushwacker flares, custom Authority Motorsports bumpers, and Pro Comp 130-watt lights round out the exterior. The 38.5x16.5 Swampers on 9.75x16.5-inch Alcoas don’t rub anywhere, despite tons of axle travel. Bushwacker flares, custom Authority Motorsports bumpers, and Pro Comp 130-watt lights round out the exterior.

The expression “when pigs fly” comes to mind when watching Ramona, California, resident Billy McKim air out his ’91 GMC. Not because it isn’t a bitchin’ truck, but because he’s able to get that much daylight between the massive 1-ton axles and the ground. Billy was told by other magazines that his truck wasn’t feature-worthy. We can’t imagine why a rig that can pull duty as a hill racer, rockclimber, dune jumper, and desert blaster wouldn’t deserve some ink.

The big GMC started life as a ’91 two-wheel drive with a 4.3L V-6, but when you get down to it, there isn’t much left other than the body and part of the frame. A GM Performance Parts 502 crate engine was set back 13 inches into the cab for better weight transfer. Backing the Rat is a built TH400 on a custom crossmember and a divorce-mounted NP205. Equal-length driveshafts connect to a Dana 60 front and a Corporate 14-bolt rear axle that were massaged and trussed by First Engineering in Ramona.

Billy had First Engineering create a custom tube front frame, and Authority Motorsports create a custom tube rear frame in anticipation of the four-link front and rear suspension. The Eibach springs on King coilover shocks are equally comfortable soaking up big-air landings as they are at high-speed desert running. In order to control the big 38.5-inch Swampers in deep sand and at slow speeds, a hydraulic steering valve from a Freightliner was fitted and powered by a Rupes Hydraulics pump. The hydraulic steering is so powerful that Billy can place a tire against an obstacle and move the truck sideways by turning the wheel.

On the inside, a 26-point rollcage (that’s not a misprint) surrounds the Corbeau buckets and Auto Meter gauges, and, as Billy found out in a recent rollover, it really protects the occupants from serious injury. A 2000 GMC body is being prepared to replace the old crunched sheetmetal, but in the meantime Billy will continue to rack up the frequent flier miles.

Comments

Connect With Us

Newsletter Sign Up

Subscribe to the Magazine

Sponsored Links