Original 1973 GMC Trucks Dealer Advance Specifications Sheet Set Part C. This Advance Spec Sheets Set were sent to Dealers so Sales and Service Staff could familiarize themselves with the new Truck Models. This Set covers the Medium Heavy, Heavy Duty Conventional, Steel Tilt, Aluminum Tilt and Bus Chassis Models. Very informative and hard to find piece for the GMC Truck Owner or Collector. It is in good condition with minor wear and soiling [see photos].