Have you not looked at the rear harness or the coinnecters to it ?
Does the car have fender mounted signals ? Those wire locations in the bulkhead connecter changed at some year model. Dont remember exactly. I think I would disconnet those for now and concentrate on the 4 main signals.
In most cases the flasher wont click/work at all without enough draw. One front signal bulb, one indicater lamp, and one fender moumted lamp, might be enough draw to make a flasher click although slowly. Trailer mounted bulbs increase the draw and cause a flasher to click faster than normal. They would overheat too which is cured with a heavy duty flasher. I hope this info is atleast some help.
