Hy Pipeliner78, as I said this age of truck is tricky to find the correct brake parts for and to give me the best chance of finding the correct parts I need a bit more information. Does your truck have a single or dual braking system (one or two brake lines connected to the master cylinder)? I did find a part number for the single brake system booster, GM p/n 3979525 = Napa p/n NBB 5479400 $381.60 + $56.00 core, hope that helps
