I agree with slick. I no longer use the 3racing diff, because the destroyed my outdrive pinion. See my earlier post.
I switched to Vaterra Kalahari diffs. The are full metal and fits. The set also includes the drive shaft pinions. No more plastic in the diffs. Unfortunately you need to buy some additional parts to complete the diffs.
Part numbers are :
2x VTR212003 --- Diff house and pinions
1x VTR212010 --- Diff outdrives , not included in VTR212003
1x VTR215000 --- complete screw set for Vaterra Kalahari, includes the screws for the diff house.
Losi 1/14 Mini Desert Truck and Losi 1/14 Mini Rally using the same diffs.
I still use the HPI A557 wheel Axles. I also switch the dogbones to HPI H72069 6x47mm(from RS4 Sport 2). They fits on the wheel axles site, but need some work at the ball to fits the Vaterra outdrive. But this is not realy a problem.
My son run this setup now for 10 sessions with 2s LiPo with stock motor and it still looks good.
I have the Vaterra Kalahari and the Kemora...both the same truck, just different bodies and tires. Also Losi now runs this truck too. It looks exactly like the Vaterra truck. So those parts may be options as well.
I can attest to the strength in the Vaterra Diffs. Been running 3s with the stock brushless in my Kemora for over a year and have never broken one.