How do I ID a 4 speed, overdrive or not?

The bearing retainer is the round piece bolted to the front of the tranny with a tube on it that the through out bearing rides. The protruding diameter (5.125) actually acts as a register for the tranny into the bell housing. You can not see it if the tranny is in the car. Plus the retainer can be swapped for a smaller one (4.80").

If the tranny shifts correctly then the lever direction on the side of the tranny is the most positive way to tell. If the levers were installed incorrectly then the tranny would not shift right (i.e., 3rd where 4th is and visa verse).