I have a 1928 10-20 and when I got it the mag was off it [ was told it did not have the correct mag on it and he had brought this E4A mag because it was original for the tractor, but never installed it], let me say first I know little about the E4A, I would like to know if I have the right one for this tractor before I spend any money on it, looking at a operators manual [ not sure if its the correct year manual ] show a piece on the mag [opposite end from the cap]they are calling starter pawl, both are E4A magnetos, but the one I have does not have the starter pawl, I see both kinds for sell, [hope starter pawl is correct name] hope I haven't confused everyone, would anyone know which one would be correct for 1928 10-20, with or without the starter pawl, or someway to find out? Thanks