[p marcott]

My 62 Chevy impala odometer jumps around like a jumping bean. What gear, how many teeth should be on the plastic gear at the base of the odometer cable at the transmission.

 

[christmascreature]

You mean the speedometer right? The needle is bouncing around?: If that is the problem, your speedo cable either needs to be lubed or possibly replaced. There could be a frayed spot in the cable and it is catching on the cable housing.