904 (32RH) Help - No Reverse

I'm not sure if the 904 has a Bellevue spring, but that's what I'd be looking at and the clutch pack clearance. My recollection is that the wrong piston and spring combination and or clearance will allow the piston to "overtravel" and engage the transmission without pressure.
Get a good rebuild manual and be patient.
Thanks for the response. Dumb question as this was my first rebuild and experience with automatic transmissions. Is there a difference in thickness for the forward friction plates vs. the rear? I should have checked clearance, but did not. I remember thinking that the friction plates that they sent me in the kit where thinner than what I pulled out. They sent all the same thickness friction plates.