A little more info will be needed, do you have part numbers, maybe photos of what you have? If I remember right, the really early pistons sold as "Jahns" were cast and sort of a budget replacement piston. Pistons sold later as JE (Jahns Engineering) were forged and of higher quality. I've seen the early forged pistons still marked on the box as "Jahns" though, so let's see what you've got. Devon