Original 1970 GMC Truck Dealer Service Manual Supplement. This Maintenance Manual Supplement covers Series 1500 thru 3500 Truck Models and was meant to be used with the 1969 Service Manual. These Manuals are what the Dealership used to service and repair your truck. It contains information, illustrations, diagrams, specifications and procedures to service your vehicle. Very informative and useful tool for the GMC owner. Good condition with normal wear and soiling from use in a Dealership.