So I got the piston in and put the trans all back together and it works perfectly, shifts into reverse with no hesitation and drives great. One suprise was that it fixed a problem I wasn't trying to address - previously when I would manually shift the truck into low, the tranny would free wheel, ie it wouldn't hold the engine, the RPM's would drop to idle and I could free rev the engine, now it doesn't do that, it engine brakes like it should. I also had to make a bracket to hold the apply piston lever shaft (the shaft that the aplly lever rides on) in now that I knocked off the boss off the OD unit that held it in place (read my previous post for more of an explanation).

One tricky thing was the piston was hard to get in because the wear ring that's on Superior Transmission piston kit. It's a split wear ring, so you have to hold the ends together so you can push the piston in the bore (similar to the rings on the pistons in your engine) What I did was hold the wear ring tight around the piston until the ends almost butted together, then put a dab of crazy glue to hold them together, then drove it home.

So if you are experiencing problems with your 46 RE/RH, try and fix it first. This is the second problem that I've fixed where I've been told "Oh it's junk, get a rebuild". The first problem was the shift governor solenoid, that fix was straight forward and took a couple of hours and cured the problem. This fix took about 10 hours in total (I could only work on it for 2 hours at a time, so that probably added some time).

Total cost for both fixes was approx $300, filter and fluid included and I didn't have to yank the tranny.

Thanks to the previous posters for their advise.