HI Sean, Jerry told me that he made just under 20 M23's. So, I trust that means 18 or 19 total. Hull numbers seem to mean little, my hull is # 75 and it is a 1979. A Stainless steel pin could be fashioned by any quality machine shop. Good luck, tell us more about the boat you are looking at. The M23 is a rare bird indeed. Bones