In order to make the change you are going to need a torque tube and a drive shaft. The torque tubes are all interchangeable. Any year will work. All the drive shafts are the same except for the very early ones that used the 370 ring & pinion. You also need to have an understanding about how to make the change, as it is not a straight forward task. You are also going to need some special tools: tall jack stands, a spring spreader, a special tool to pull the pinion assembly out of the banjo, and a tool to remove the pinion from the overdrive stub shaft.
Torque tubes and drive shafts are abundantly plentiful because so many have been removed from Model A's over the years to accommodate the installation of various overdrives. Because of that they have little value and hardly anyone brings them to swap meets. I have at least a halve a dozen hanging around and would be glad to give you a set if you stopped by the house.
My advice is to contact the local Model A club in your area and ask it they would canvas their members to see if anyone has them. Most people who install an overdrive end up storing the torque tube and drive shaft somewhere on their property with no further use for them.
Tom Endy