GMC Sierra All-Terrain HD Concept

January The GMC Sierra All-Terrain HD concept makes its debut at the 2011 Detroit auto show. GMC took a Sierra HD crew cab. Ripped out the existing long bed and install a five-foot, eight-inch short bed from a half-ton Sierra. Add in three inches more of ground clearance, for a total of 11.8 at the skid plates. Install remote-reservoir Fox Racing off-road shocks, allowing for huge wheel travel front and rear. Combine with front and rear jounce shocks for better rebound control. Add 20-inch wheels shod with 35-inch tires that combine with the suspension changes to widen the track by 4.2 inches. The best part is a 6.6-liter Duramax turbo-diesel with 397 hp and, 765 lb-ft of torque.