the inner shaft is the same but be careful with the outside diameter. you will hit the anode-trim fin on a alpha if not careful.
you can get a flat one if you have power steering or just break the one you have off.
i have a couple of mirage II vented props that were 15" dia.(i think) after changing the anode to a flat one they worked.
the dealer i bought them from said just break the tab with a hammer. as stated i bought a new flat tab. breaking didnt seem like a good idea.