I am looking for a used rear cyl intake cam shaft (the one that also turns advance unit and points cam) for my '75 ironhead sportster. I can get set (4) new but I just need the one....Bad advenced unit broke timing bolt off in the cam shaft and I am having difficulties. breaking bits off in it too. got shaft out. trying to find machine shop to help. May have to replace. looking for good used one...Im sure the a lot of ironhed (1959-earl1984) engine parts out there...Anybody got websites or phone #'s to find this part?