By Ron Ceridono – Images Courtesy of AME Offroad & Rapt Visuals – Illustrations by Tavis Highlander
In the Jan. ’24 issue of Classic Truck Performance we revealed Art Morrison Enterprises’ (AME) new AME Offroad 4×4 chassis for 1973-1987 Chevrolet/GMC pickups and 1973-1991 Blazers by showing the construction of the prototype. We can now show the finished product, and it was well worth the wait.
This project began when Matthew Jones, president of AME, found a 1974 GMC 2500 pickup that had been retired by the Mapleton, Utah, fire department. The goal for the truck was to use it for developing a 4×4 chassis that had the capabilities of a high-speed off-road truck, the articulation of a rock crawler, with the handling and performance on the street that AME is famous for.
The foundation for the AME Offroad 4×4 chassis are framerails made from 2×4 and 2×6 3/16-inch mandrel-bent tubing. Far more rigid than the early OEM C-channel framerails, crossmembers and gussets are placed to ensure torsional rigidity, and the front coilover towers feature a removable crossmember for added strength and ease of assembly and maintenance (see the Jan. ’24 installment for complete chassis details).
Under the front of the truck is an AME-fabricated axle housing with a Currie centersection and 35-spline inner and outer axles from Dutchman that use 1480-series U-joints and bolt-on wheel bearings. In the rear is another AME axle housing and another Currie centersection. ARB Air Lockers are used front and rear with 5.13:1 gearsets. Fox coilovers with remote reservoirs and Eibach springs combine to provide nearly 12 inches of suspension travel up front and 13 inches in the rear. Optional pneumatic bumpstops fore and aft keep the suspension from bottoming out when the going really gets rough.
Under the hood of the GMC is a Chevrolet Performance 6.6L L8T (403ci) direct-injected crate engine. Factory rated a 401 hp, this engine has been treated to ported heads and a Chopacabra camshaft from Texas Speed that ultimately netted nearly 600 hp at the flywheel. The engine exhales through headers from Ultimate, they connect to 3-inch pipes from Stainless Brothers that lead to twin catalytic converters and Venom twin inlet muffler with a single 3.5-inch outlet. There’s also a set of Granatelli exhaust cutouts just for fun.
Making all the engine’s electronic bits and pieces work is an ECU and wiring harness from Speartech, the front accessory drive is from Vintage Air, and a Holley oil pan was installed for more differential clearance. The unique air cleaner from UMP connects to the throttle body with a custom 4-inch aluminum tube while fuel is supplied by a stock-style Tanks replacement gas tank with an internal fuel pump. Keeping the engine cool is a radiator from DeWitts and mounted to the firewall is Wilwood tandem master cylinder and hydroboost unit.
Providing 10 forward speeds is a stock GM 10L80E automatic transmission that connects to an Atlas transfer case from Advanced Adapters. The Atlas transfer case is unique in that it allows selecting high/low ranges for front and rear drive independently, that is one can be engaged with the other in Neutral. To keep the transmission temperatures in check a fan-forced Fluidyne cooler is located under the bed (next to the oil cooler also by Fluidyne).
Inside the cab the remarkable original saddle vinyl interior (factory option 674) remains, although Dynamat insulation has been added and McFarland Upholstery installed a new rubber floormat. The dashboard remains stock other than the addition of an ARB compressor and locker controls, new Dakota Digital gauges, and a Vintage Air climate-control system. To make sure all the electrical items work as they should the original chassis wiring has been replaced with a harness from American Autowire.
Following the utilitarian theme inside the pickup bed is a toolbox that contains the air compressor, air tank, two batteries, electric parking brake computer, relays, and fuses. The aluminum box has been powdercoated white by Northwest Powder Coating in SeaTac, Washington, to replicate the original fire truck appearance. The custom front bumper that mounts a ComeUp winch, the rear bumper, and wheels have also been powdercoated to complete the look.
AME’s rejuvenated GMC is an absolute success by any standard. It not only looks great but it has met all the goals set for this project by performing brilliantly on road and off—it really is a true double-threat truck.
Check out this story in our digital edition here.
Source
Art Morrison Enterprises
(800) 929-7188
artmorrison.com
