Does anyone know what retains the speedometer drive gear on C6 transmission with a short tail shaft? On mine I can spin it with my finger trough the cable hole.

 

That doesn't sound good. I don't know, but was under the impression that they were captured between two components on the shafts. At least that's how I think of them on 4wd's where the gear is in the transfer case. In that case maybe the rear output shaft nut holding the yoke in place would allow movement if it was working loose.
But this sounds like a 2wd truck with slip yoke? If so I'm out of my depth completely as to what's inside the housing.

Good luck. Maybe it's a quick, easy and cheap fix.
Here's hoping anyway!

Paul

 

on some of the manual transmissions there is a detent in the shaft and one in the drive gear, a small ball bearing shaped piece locks them together. I assume that the drive gear should be a snug fit

 

yes it is a 2wd but has a split drive shaft. Short shaft from trans to idler bearing. rear end shaft has slip joint end to idler bearing..

 

Guess I am just going to have to tear it down and find out. I wanted to get all the parts together before I broke it and then find out I need something that will take a while to get.