Machine description: Detroit Series 60 6 Cylinder 11.1 L Diesel 350 hp Engine, 1989 US EPA Label, Eaton Fuller 10-Speed Manual Transmission, 285/75R24.5 Front Tires, 11R24.5 Rear Tires, Air Ride Suspension, 170 in Wheelba... more info about the 1990 GMC WCA.