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.