Original 1973 GMC Truck Emission Control Systems Required Maintenance and Warranty Information Booklet. This would have been included with the Owner's Manual when you picked up your new vehicle. This pamphlet covers the Detroit Diesel Engine Models L-530, V-53N, L-71N [Four Valave], V-71N [Four Valve], V-71N [Two Valave] Coach, V-71N [Four Valave] Coach, L-71T and V-71T Engine Families. It is in good condition with minor wear and soiling [see photos].