The gears are shattering cause they're hardened. You have to use tungsten carbide bits on hardened steel. TRX spyders (without shaft) are T and E Maxxes diff weakest part. RRP stuff is weaker yet (heat treating is not the best).

I've had decent luck with FLM diff cup upgrade - you get a new ring modded to use 3mm vs the 2mm stock screws and a better arrangement for the spyder cross shaft - its kinda keyed into a slot in the FLM alum diff cup so its less prone to move and bust spyders. The other thing needed are alum diff cases - even the 4 screw cases from 3.3 will not be strong enough to resist flexing that lets R&P pull just enough apart to start stripping teeth. Buy the cheapest alum diff cases you can find and a set of alum diff collars too.

The alum diff cases and the flm diff cup will last for a while - stronger than stock. The next step up is to HB diffs in flm hybrids or UE 6 or 8 sypder diffs. I've been thru this all this with small block to big block swap on Tmaxx.