The 'bolt covers trucks from 1916 to 1972, so as 55 Shaker mentioned... if you want a useful answer, we are going to need more information.
kinda info we need:
year model
chevy or gmc (some of the older trucks had very different wiring setups between the two)
model number for ton rating
engine, trans, any known modifications may be an issue as well.
-W
