1976 three on the tree question

So far as I know none of the "more modern" Mopars ever came with a 3 speed overdrive. When people say that what they are referring to is a 3 speed stick (often yes, column shift) with a OD unit tagged onto the tail shaft, shifted usually by an electric actuator.

Just to be clear, the A833 OD 4 speed is a 4 speed in which Chrysler re-geared the THIRD gear to be an OD gear. The ld 4th gear is not a gear. All traditional US 4 speeds and 3 speeds in passenger (and light truck use) the "high" gear AKA 3rd in a 3 speed, 4th in a 4 speed, were a shaft coupling, and not really a gear.

Chrysler turned the 3-4 shift lever upside down so that as you shift the shift lever 1-2-3-4, the transmission is actually shifting 1-2-4-3, IE 4th being the "new" 3rd is "straight through" and the old 3rd gear becoming 4th has been re-geard as an OD