Machine description: Mack 6 Cylinder 672 cid Diesel 283 hp Engine, 1980 US EPA Label, 6713 Engine hrs, Mack Manual Transmission, 425/65R22.5 Front Tires, 11R22.5 Rear Tires, Rubber over Walking Beam Suspension, 230 in Whe... more info about the 1981 Mack DM686S.