I have a Ranger with a serial number about 1000 lower and a couple with numbers about 2000 higher plus some very late 29-A & B's andewill try to compare sometime after this weekend - I know there are some small differences in early and late bolts but had never had firing pins that would not fit - only have replaced a couple though. I am probably not going to disassemble any bolts though, I will only be able to compare what is visible on a complete bolt.