Ive got my 1972 904 out for a rebuild after it wouldn't go into Drive at the track under full load. Upon tearing it apart the pump housing face is worn down as is the pump gear set. So I went junkyard scrounging today and found one lone 904 non lock up sitting in a school bus with a bunch of other long forgotten trannys. It had ASPEN written on it in crayon. Well after pulling the pump paying the guy twenty bucks and getting home to tear it apart to clean it up and make sure it was good I noticed it is the spitting image of my pump except mine has 3 staked check balls in the pump housing and my JY pump body only has 2 check balls staked in it. The 3rd hole is there and the circuit looks identical in where it runs to but there just isnt a check ball in it. And no it didnt fall out there is no mark where one was ever staked in place. The pump has a Chrysler front seal so I assume its a stock untouched unit. So has anyone ran into this before? Do I just stake in a check ball to my JY pump or leave it alone or can I not even use this as a replacement? Also can a 1979 lock up pump housing be installed into a non lock up trans and work? I have a mint looking one I pulled out of a tranny I had in my barn just to see what the differences were. I saw a few different ports but even the 1979 lock up 904 pump has the 3 check balls in it.

Only the lockup reaction shafts have the three check balls. The non lockups have two. If that third ball is in there in a non lockup trans the converter won't fill properly.

Youre right, geez my memory. I took the JY pump to the shop this morning and my 1972 non lock up had only two check balls. Thanks

Unless the guy wanted stupid money, I'd have brought the whole trans home with me. They aren't getting any easier to find.

Can the third ball be removed and the support used in a non-lockup unit or are there other differences in the pump plumbing?