I'm rebuilding a 1965 904, and found that the swedging had let go and the checkball in the forward clutch piston had fallen into the drum. No problem, I think to myself, I've got a '63 904 for parts, I'll just grab that one. Nope, the checkball in the older trans is in the clutch drum, not the piston. So I'm wondering, are the pistons the same from '65 and up? Obviously I don't want to find/buy one from a newer trans and have it be different.