Model Condition Price Qty  
MD7739-74 Very Good $29.00
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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
Cab, Engine and Chassis Wiring - HV/JV-70013; 75013; JV-80013; 85013 MD-7739"
1
Included
This item is original.
11.00 x 8.50 x 0.10 inches
MD7739-74
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This book covers 1974 and early 1975 GMC and Chevrolet 70, 75, 80, 85, 7000, 7500, 8000, 8500 Conventional models also known as HV or JV, equipped with the 6V-53 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 third digit should be a V for the 6V-53 diesel engine, and the 6th digit should be an 4 for the 1974 model year or a 5 for 1975.

This diagram covers 1975 models built prior to March 1, 1975. If you have a 1975, to find out if yours is a early-year model (built before March 1, 1975), check the last six digits of the VIN, which should be smaller than 590000 for GMC or smaller than 140000 for Chevrolet. See the mid-1975 diagram if the last six digits are larger.
1974-1975 Chevrolet 70-90 Series Heavy Duty
1974-1975 GMC Series 7500-9500
1974 1975 Chevrolet 70-90 Series Heavy Duty 1974 1975 GMC Series 7500-9500