D12 12.1 L Diesel Engine, Engine Brake, Differential Lock, 12500 lb Front Axle, 38000 lb Rears, 3.58:1 Axle Ratio, 50350 lb GVWR, Air Ride Cab, 295/75R22.5, Air Ride Suspension, 190 in Wheelbase, Air Sliding 5th Wheel, Dual Fuel Tanks