A-904 - Five Clutches, Anyone Done that?

Here's where the problem lies and I'll try to explain it to the best of my ability.

Here are the parts that are different from the 4 disc to the 5 disc non lockup 904

input shaft
rear clutch drum
reaction shaft
front clutch drum
front clutch piston

Now you can physically fit a 5 disc front drum in a 4 disc trans by clearancing the reaction shaft to clear the drum as it's deeper. The problem is that the splines that engage the front clutch discs on the rear clutch drum are not deep enough to fully grab the last disc. It may work for awhile but not long. Ask me how I know.

You can't just put the 5 disc rear drum (I don't mean 5 rear discs) in either as the size of the single seal ring that goes into the reaction shaft is different, it's too big. So you need the five disc reaction shaft to match. Great, but now the 5 disc reaction shaft requires 2 seal rings on the input shaft and the 4 disc input shaft only has 1, plus it's smaller. So no big deal you say right, just get a 5 disc non lockup input shaft. And there is the rub, you can't find them readily. They were only made a few years when there where lockup and non lockup trannies available in the same model year. As far as I know I got the last two and my buddy has one of them.

If you are lucky enough to find an input shaft you can make a non lockup reaction shaft from a more readily available lockup R/A shaft by removing one sealing ball used to seal off one port. If you compare a lockup to a non lockup (whether it's for a 4 or 5 disc) you can readily see which ball needs to be removed.

Is it as clear as mud now?