I've read every post reguarding the NTC3 on this site, the HPI site, the RC Car Action site, and the Associated site. To the best of my memory, other than specific one-way related problems, I haven't read anything about blown diffs, broken drive cups(?), or broken drive shafts(?). I have not personally seen or heard from any fellow racers about this either. I currently run an IRS electric TC3 front drive cup in one of my NTC3's with the FT blue alum drive shaft and the stock plastic brake hub. I own and have used the Hardcore alum brake hub & driveshaft , and the GPM driveshaft as well. The only parts to wear are in fact the aluminum parts, similar to what you'd see in an electric TC3 with aluminum outdrives and no pin cushions. I have yet to see any aftermarket company offering steel drivecups, let alone steel (or any other metal/alloy) ring & pinion gears for the NTC3. If you or anyone else has that info. pass it on, I'd gladly volunteer to be the test pilot.