There was a change in propeller hubs from a rubber shock hub to a “Slip Clutch” hub designed to slip under a certain overload as when striking a submerged object. This would account for the differing part numbers. Shear /drive material was changed also, with the slip hub having a stronger pin, usually stainless steel. Props are interchangeable as long as the correct drive pin is used. This chart shows the newer part numbers
