Original 1979-81 GMC & Chevrolet Truck Dealer Parts Catalog. This Parts Book covers the Medium Duty Steel Conventional Series C5D, C6D, C7D Models. This is what the Dealer used to order Factory Replacement Parts to Repair your Truck. It has Part Numbers, Group Numbers, Description, Quantity and Application with no Illustrations. It is in good condition for its age with normal wear, blemishing and soiling from use in a Dealership [see photos]. The pages are loose with no binder. Very rare and informative piece that will be a valuable tool for the GMC or Chevy Truck Owner or Collector.