If you want' strip down your diff, and take photos as you go. Post em and we can see what condition they are in.

The key points to look at are that the main gear still has all it's teeth, that the input gear has all it's teeth and that hte two mesh properly.

Next open up the diff cup (Take the main gear off the cup) and check that hte output gears and spider gears have all there teeth and that hte insides of the cup arn't trashed (There are two rails teh spider gear axile fits into they shouldn't be trashed)

FHM has a good writeup on rebuilding diffs here http://www.rctech.net/forum/showthre...=49101&page=14
Here is an other write up on diff building http://www.rcnitrotalk.com/2004/t-ma...tial-shimming/

I am still looking for the guide I followed, but these should help