In a 1956 Thunderbird, the speedometer is running backwards. I put a drill on it and when it turns counter clockwise, it goes the right way. However, when I hook it up, it turns clockwise and runs backwards.
It almost sounds like the gear that drives the tachometer cable from the distributor is incorrect, and maybe from another car? Check online TBird catalogues for pictures of the correct drive gear and compare them with yours. Just a suggestion, cause I'm at a loss to explain your situation otherwise. Good Luck!
