904 parts upgrades

The only 2 things I can think of is A&A's front clutch return spring assembly that replaces the original spiral wound spring and a 1-5/8" wide kevlar front band. Other than the manual VB that's how I built my 904 that's behind a stout 408 with a 4000 stall and I've beat on it for about 6 yrs. with no problem

EDIT: just thought about the planetaries. Do you know what it has in it? You should be running steel 4 pinion planetaries