1948 F1 Distributor Identification

[[email protected]]

Hi everybody,
I’m looking for a distributor, used or new for my 1948 F1 with a 239 in.³ eng.
can anybody tell me the distinct differences between distributors in these model years? I believe the shaft is different at the bottom. Distributor that I have found has no extension below the gear. Can anybody clarify what distinctions I should look at?
I will try to post pictures of two distributors that I have.