when you say you shim both the ring gear and pinion gear where exactly is that? and how many shims do you put in it to get max tooth engagement without any bind?

and 46u maybe you can help me, when i hold the diff case and the 38t gear together and spin the cup joint the other turns in the oppisite direction, but when i put the four screws in the diff assembly i dont get any diff action is it suppose to move freely when i turn the cup joint because its sort of difficult to move the cup joint and get the other to move the opposite direction. and i was wondering if you can give me a little help on this problem of mine thanks.