Here is a couple pics. I picked up a Proto 4749 it is close but won't work. It is 24 Tooth. The part on the back of the gear that sticks through the back of the ratchet head is too big. I guess i could put it on a lathe and turn it down just a bit. But i also lost the little ball. Measurements across the gear are .647", and the back of the gear is .403". Battery on the digital was dead so these are the best i could do with the old fashion caliper.