If it shifts three times, then it is an AOD, also, is there a second cable going to a lever on the side of the trans next to the main shift linkage, or what does the shift indicator read as? "PRND21" or PRN'OD'D1".
If you are going to use a Motorcraft carb, their are certain models that use an AOD-specific throttle lever. You can use most aftermarket carbs with the AOD transmission. BUT you must make SURE that you get an AOD throttle bracket that mounts to the throttle lever on your particular carburetor. Holley makes one for their carburetors, and so does Edelbrock.
Then, make SURE you get the transmission throttle valve pressure correct! If it is not adjusted correctly, you will destroy your AOD in a very short time. I would suggest going to a reputable transmission shop to make the transmission adjustment.