I got a 91', second gen, check if the wiring harness is messed up(the wiring harness has to parts to it) if it is, then of course your going to need another one, if not, unhook the wiring harness, there should be two clips, look at the new head unit wires, and look at the wiring harness wires, color match them, some of them would be the same color, but theres a difference, the colors that are the same have a little difference in them becuase they have like a black or white line going throughout them showing that its the different wire to be matched to them. Any more questions bro, ill be happy to help.