Timing sprockets

I think the 59-63 singles used 16 tooth if I remember right.

I don't have any earlier 15 tooth singles so I can't say. To me the alternator models were the best but that's my opinion! Theoretically you should be able to use either but there must have been a reason for the change. Less tooth wear perhaps?

My 1951ES2 has 16 T sprockets as standard, so as long as they both have the same tooth count, there should be no problem.