Just picked up a 1969 Buick Wildcat 2-dr hardtop. I noticed that the speedometer was not working. I looked beneath where the cable connects to the tranny & saw that the cable was not even connected & tucked away in the frame. Where the cable would connect on the thm400 is a type of freeze plug block. I know they did this on racing applications where mph does not matter. I ran the plate on the tranny & its from a 1979. I would prefer numbers matching, but this is the hand i was dealt. I'm fully capable of removing the plug & installing the speedo gear & even the one on the output shaft if its missing, but my question is what # gear do i need for the output shaft & speedometer gear for my application??.
Assuming you are looking for a "close to correct" speedo reading, this is dependent on rear gearing and chosen tire diameter
