63 slant 6 904 transmission seal and o ring question

Automatic Kings in Riverside, Ca. on Rivera street sells them for $16. And they do ship. But you might have to order that rear seal separately. I get those at O'reilley's.
Will check this out. If it's that cheap I'll definitely be ordering a set... Maybe 2 as I have a spare transmission. It was supposedly completely rebuilt but if it's been sitting at all the same seals and o-rings could use replacing. Previous owner upgraded transmission and rear end as they were adding a turbo to the 225 slant.