Doug,
The piece in your last photo is the speedometer driven gear.
You can take that out to inspect its condition.
If all the teeth look good. You may have a bad (or, more likely, missing) speedometer drive gear. It is mounted on the forward yoke of the 4-speed u-joint assembly which resides inside the enclosed driveshaft's u-joint enclosure. You would have to disassemble the u-joint and drop/raise the drive shaft enclosure for removal of forward yoke and for inspection for the drive gear.
