Starter identification needed

[miwi]

I hope that someone could help.
We had found a few starter that together with a Model A project car. Two of them are Model A 4 engine, but there are two other starters that looks the same as the Model A starters. But there thread of the shaft where the Bendix drive is as a different direction.
The Model A starter are left handed, while the others are right handed. All starters have a 3 bolt pattern, the body has the same length and diameter and they are all 6 V.

We are a bit concerend if the two right hand thread are for a Model A engine.
We were thinking that the position of the starter is different on these engines. But why and where were such engine were used?
Thanks for your help