32 coupe speedometer drive gear needs replacing, how.

[glennpm]

Originally Posted by Terry,OH

The gear on the drive shaft is splined and fits over the splined drive shaft, so it should not turn with your finger. With the snap ring out of place the gear still should not turn, the spline shaft goes into the U-joint.
Check again it is possible the gear feels like it turns by hand but may not be. There could be a problem with the turtle.

I agree with this and don't see how it is possible that the splined nubs on part 17285 could have sheared off. If all of them were sheared off, there should have been a lot of broken pieces when you took the turtle off. I too think your turtle gear is the problem as shown above by rockfla.