This CD rom includes complete reproductions of the original printed paper manuals that the dealership mechanics used to repair and service cars. It includes 1980-1981 Chevrolet Truck Medium and Heavy Duty Service Manuals 3 Volumes This CD rom includes complete reproductions of 3 original printed paper manuals that Chevrolet mechanics used to service trucks. It includes the 1125 page Medium Duty Service Manual 1980 Chevrolet, the 1273 page Heavy Duty Truck Service Manual 1980 Chevrolet, and the 223 page Medium Duty Truck Service Manual Supplement 1981 Chevrolet. With step-by-step instructions, clear pictures, exploded view illustrations, wiring diagrams, schematics, and specifications. This CD covers all 1980 and 1981 Chevrolet Medium Duty truck models including P4 Forward Control Chassis, B6 School Bus, C5-6-7 series M.D. steel conventional cab, and W6 and 7 M.D. steel tilt cab and all Heavy Duty Truck models including 80 and 90 series models including conventionals, tilt cabs, single axle, and tandem axle vehicles, with both gas and diesel engines.