77 302 stepside. It was a basket case. Trying to get wiring correct. I have no pigtails in the rear. Only cut wires. It had the rear lights in a box with cut wires with colors that don't match the wires on the harness. I have checked out all the wires at the rear of the truck with a test light and I seem to have power to all. I have not checked out the back up lights as I am alone and don't know confidently if the ebrake even works yet. I think I am good with power to the tree wires on each side of the truck that will go to the lights. My question is the lights. I have what appear to be correct lights. I have three wires coming out of the lights a red, white and black. What I cant find is, what bulbs or filament are responsible for what function. In other words, I do not know what bulb the signal light, running, and brake light are. I have read many threads first but have not found this information. Thanks