Machine description: Mack E7 6 Cylinder Diesel 400 hp Engine, 1990 US EPA Label, 3990 Engine hrs, Manual Transmission, 14300 lb Front Axle, 38000 lb Rears, 52300 lb GVWR, Aluminum Front Wheels, 315/80R22.5 Front Tires, 11... more info about the 1990 Mack RD688S.