Spent way too long troubleshooting an odd flasher problem today. Everything worked fine, but when the eBrake was on it would buzz instead of flash. Checked all the wires, lights, switches and it had a new flasher unit installed. Tried a different new flasher unit from my 71 where it works just fine. Nothing made any difference. Until I got an old flasher unit from a 75 and installed it. Now everything works fine.
Anyone know of a difference? The PET shows two versions, early and late, BUT the part numbers are the same.