A904 has reverse no foward
If it worked and then quit, something wore or broke. The valve body may or may not be an issue, or contributing.
The forward clutch is engaged in all forward gears, if you suddenly lost forward gears and then it came back when cool, I would suspect clutches and steels or a lip seal. A pressure test should reveal a lip seal issue.
You said clutches looked good, how so? Was there still grooving visible on the faces? Or were they perfectly smooth? What was the pack clearance?
Well when it quit I had nothing, you could only let it idle, if you hit the gas the engine would rpm real high, I had at firsts though maybe the linkage come undone, but that was not it, turned off the car, without knowing, restarted to check if i had reverse, then I had everything back for about 1/4 mile etc. since the trans has been rebuilt with less than 5,000 mile on Ill wager, I figured maybe the front pump or the torque converter, when finding out prices some trans place's told me that it sounded like it was sucking up something, clogging, which would be why I lost everything, until I shut down and restarted. Now to be fair I had planned on replacing the convertor with a high stall anyway so no biggy there, I really did not care if it was the converter or not since I was pulling the trans anyway now was the time to put one in so I got a 2500 stall, also this is a lock-up trans ( found out the hard way) When I removed the pan and filter to inspect for anything I did not see anything to wright about except for the plastic speedo gear pieces on top of the filter. So natch I figured that must have been the issue, after removing trans, I did inspect the first two drums and clutch packs. They look new, not worn at all, one steel had a bit of bluing from getting hot a slight sent of burnt oil, but everything looks good including fluid that I drained, even in the pan there was debris you would expect to find, did not go further, replace front pump because we found a gouge, so just for good measure. reassembled. Now we run it with jack stands through all gears, you can tell its in reverse, however when it is in N-1 tires will go forward just not with the car on the ground, engine does not over rev, it acts like it stays in park or neutral. Its does take a bit of pedal to get them to move however. I will do some pressure check's, however I do not know which ports to use, so some help there would wonderful, also before all this, there was a noise in low gear that happened ever since I got it back, its hard to describe with words, It was like a slipping noise, it would happen as you got moving, just when you would hit the gas to go , one time every time, the morning that it quit, that noise was like an extended version of it, it never did anything like hard shifting or anything, just that slip like noise, I wonder if something in the VB has been going all this time and just let loose, The car don,t move so I don't hear it now, maybe that might help as well. Again this sight is great I hope I can help out some folks as I gain some exp with what I am doing, and thanks in advance and thanks FABO.