Condition Price Qty  
Very Good $29.00
This is the original wiring diagram printed by GM for dealer mechanics. You can follow the wiring in your truck from bumper-to-bumper. It will help you to understand connector configurations, and locate & identify circuits, relays, and grounds. Although the schematic is in black and white, the color of each wire is noted. You will not find this diagram in your shop manual. The schematic measures 8.5" x 11" when folded up, and opens up to 11" by 38". The diagram pictured is an example of this type when folded, but is not the actual diagram for your vehicle. Buy now for the best electrical repair info - the factory wiring diagram.
general motors
1975 Truck Wiring Diagrams Medium and Heavy Duty Models MD-14071
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This book covers 1975 GMC and Chevrolet 7000-7500 Conventional models also known as HY or JY 70013 or 75013 equipped with the Caterpillar 3208 diesel engine. See my other items for other engines. To verify that this is the correct diagram for your truck, you can check your VIN code. The 2nd digit should be an H or a J for the heavy duty conventional cab, the 3rd digit should be a Y for the 3208 engine and the 6th digit should be a 5 for the 1975 model year.
1975 Chevrolet 70-90 Series Heavy Duty
1975 GMC Series 7500-9500
1975 Chevrolet 70-90 Series Heavy Duty 1975 GMC Series 7500-9500