It gets a little complicated, if the 904 is pre-'78 you can get in trouble mixing parts; if the 904 is '78 or later non-lockup you can use the later 5-clutch drum and pump but if the 904 is pre-'78 you'll also need the later input shaft and rear clutch piston retainer.

Or the earlier pump can be machined to accept the 5-clutch drum.