What A-833 is this?

The input shaft retainer is usually larger on an Overdrive. A measurement of that is I could tell tale sign.. if you're paying good money for it I would want to open the side case. It's only 10 bolts and it pops off easy. If the gears progressively get smaller then it is a 4-speed. If one of the middle years is way larger and it doesn't get smaller to larger evenly across the gears it's an Overdrive.. besides that you want to look inside of it and make sure it's all clean and oily and not Rusty and been sitting around...