I forget what it was caused but a lot of Fords used that little box on the back of the cluster about and inch and a half long, 1/2 wide with2 wire stud terminals ? UPDATE... it's called a constant voltage unit. you might have to wire one in if your donor cluster had one.. For Wiring Fords before the computer digital units I use early Mustang wiring diagrams. Google Hammar mustang wiring diagrams, I don't know how to give you an easy link.
Last edited by timothale; 12-09-2012 at 08:45 AM.