Thanks for letting me join. Looking for info on the speedometer drive gear on a C4 transmission. I have read that the gear is machined on the output shaft and the only way to change is change the shaft. I have also read on other forums there were exceptions to this 'rule'. Does anyone know what this exception is? Mine appears to have the changeable gear like on a 3 speed manual. My C4 is out of a 65 Mustang. I know all about changing the driven gear. I might also mention that this not in a Mustang and I am using an aftermarket speedometer, but this has nothing to do with info that I am seeking. Thanks. Mark.

 

The driving gear on the trans output shaft is usually movable by just depressing a spring retainer and sliding the gear off. The tail shaft housing has to be removed to do this as you are probably aware.There were different colored driven gears that were available as a unit to connect the speedo cable to.This goes back a little and I would need to refresh what was available and what kind of adapter you might need. There was a time we used to measure the revolutions the driven gear went and had a chart to assemble an adapter to provide the correct speed and odometer readings. I don't know if such a kit is any longer available. You might check this out with a few dealership parts departments.

Rental places that charged according to miles run used to have these kits because their income from a rental was dependent upon miles run so that was important.

 

Thanks for the response. The reason I asked was that in order to remove tail shaft I would have to pull engine and transmission or raise the body. My 23 T bucket has the body dropped 3 inches on the frame. There is very little to zero clearance to remove upper bolts much less jacking unit up to clear rear mount. I dont really want to spend 300 on a ratio box from speedo shop.I don't mind doing the work if I knew for sure about the drive gear being replaceable. Got more time than money. Thanks again for your response. I will have to investigate further.