Speedo Gear Question

[Synestran]

Hey guys,

Searched around on this forum for a little while and couldn't really find an answer to my problem.

When I bought my truck (1969 C10 292 3OTT), the speedometer wasn't working. Replaced both the speedocable as well as the white driven gear and still it is still not working. Some times if I take the driven gear out and put it back in, the speedometer will bounce but not be close to the actual speed and barely go passed 15 mph. Would this been that the drive gear is worn out or something else? I've taken the cable off the back of the speedometer and noticed that it does not spin unless the bottom portion is connected to a drill so I'm guessing it isn't connecting with the drive gear in the transmission.

The drive gear inside the transmission is blue in color and I'm not sure what gears I have in the rear.

Any help would be appreciated.