Best thing to do would be to fit ceramic balls as the standard ones are not the best. Make sure the plates are flat by grinding them down on some wet and dry paper.
Make sure when yo rebuild it to use some good quality black grease on the thrust race and some better quality diff grease than the stuff that comes in the kit. Build the diff correctly and it will last for ages between re-builds.
If you would like some ceramic diff balls give me a shout as I have loads of packas availible to sell at a good price
I don't believe Team C do a re-build kit. So you would have to purchase the items seperatley.