I was researching why I lost all forward drive on my 60e and was reading a post by another performance transmission shop and he said something interesting. I'm not sure if its factual or just opinion but he said you're never supposed to use an aluminum clutch piston with steel forward clutch piston in the input drum. Nathan kind of questioned it when he saw it and we put it back in. I'm not sure if there is a basis for this builder's opinion.