I asked this a while back.... mixed replies and some good info.
I fitted a gear diff in the 22, added 3k oil. and worked very well in the dry, consistant and smooth and more power out of the corners.
But, when it gets a little damp. then its a real hand full.......
I was advised to put thicker oil, prob 5k and that will help but have not tried it yet. But i continued to use the car as is in the wet, and got used to it, just trying it really. and being lazy..... haha.
I think with the thicker oil as people said it would have done the job, and its a fit and leave job with gears. simple.
But if your racing at the higher level, then i guess balls seems to work better if the top lads use them. They are of course adjustable.
So, if club fun racing and easy of maintenance, then go for a gear diff.
If racing higher level, Balls is the way......
selling my losi 22 now with both diffs etc, as going back to schuey accross the board again. but nothing against the 22, Love it, gears or balls........... toughest car i have owned, so far!