* Truck model: Is it a C10, C20, C30, Silverado, etc.? Even within those categories, there were variations.
* Options: The wiring harness changes depending on options like power windows, air conditioning, cruise control, etc.
Your best bets for finding a wiring diagram are:
1. Repair manuals: A Haynes or Chilton repair manual for your specific year, make, and model of Chevy pickup will have detailed wiring diagrams. These are usually available at auto parts stores or online retailers.
2. Online forums: Websites and forums dedicated to classic Chevy trucks (like the Chevrolet Truck Owners forums) may have members who have scanned diagrams or can point you towards a source. Searching for "1987 Chevy [your specific model] wiring diagram" on these forums could yield results.
3. Dealership (unlikely): While a long shot, a Chevrolet dealership *might* have access to old wiring diagrams through their parts department, but this is not guaranteed and may come at a cost.
4. Online parts retailers: Some online parts retailers that specialize in classic car parts may offer wiring diagrams as downloadable PDFs. However, this is often tied to buying other parts.
Remember to specify the exact model and any relevant options when searching. Good luck!
