1975 GMC Trucks 7500 Conventional Sales Folder. GMC Series 7500...Money Makers. GMC's 7500 Series models offer a compact Cab and Chassis design that delivers excellent weight distribution on long and short-haul runs. Available in sing and tandem axle models with available proven V8 gas or 6-cylinder Detroit Diesel power. Durable cab construction offers reduced sound levels for driver comfort. Doing it automatically. Allison automatic is available. Specifications on the back. ADV. 75-12 (8-74)