Back in the early '80s I changed the fenders on my '68 VW bug to fiberglas flares. I kept the OEM taillights and wiring but the lighting went haywire. I went on a cruise (usn) and put my bug in a VW shop to try to figure out the problem. After a couple of weeks I returned to find that even the shop couldn't fix the wiring. I got my car back, no charge, and had it fixed half an hour after I got home. Yeah, at sea I figured what I did wrong and fixed it with 2 lengths of wire and 4 terminal ends.