The easiest way to make the engine work is to piggy back the engine wiring harness to the truck wiring harness. I had the complete chassis harness from the Donner truck, then used a FSM to figure out what wires that I needed and what I could get rid of. I used a separate fuse block for the engine, so that way, if any problems came up. Trouble shooting would be easier. The engine harness will need 12 volt battery power, 2- 12 volt switched power and all the grounds hooked up. That's all I can think of off the top of my head. If I can think of anything else I'll post it. Good luck, it's actually pretty easy to pull off the swap. Carl