Im not sure what all years are the same, but I have a 84 and swapped all the internal out from a 91 suburban and they all work no problems the plugs are the same for the regulator but when you go down the wiring harness the plugs are different. If you get a donor and the plugs are different all you have to do is pull the pins that the wires are connected to out of one plug housing and put them in the other plug housing.