That SUCKS! I havent had any issues with my Revos drivetrain at all. Im running the 2200 on 4s and the only thing thats giving is the rear driveshafts. It keep streching the plastic where the + type metal pin is. But thats $20 to replace them on both sides every few months. I did the math and the 2650 is turning out the same RPMs as the 2200 on 4s. Im assuming the 2650 on 3s would be puttin a little less torque out aswell. Maybe your doing something wrong. ??? I don't know??? Maybe try shimming the diff. or something. Im guessing you checked/rebuilt the rear drivetrain. Would have noticed something outta place by now. I got my E Revo used, then dropped the Castle in it and Ive never had any issues yet. "Knock on Wood" But I never stripped my diffs in any kits and Ive had some really unbalenced wheels. Check out http://www.revo-world.com/forums/index.php
Thats a site dedicated to the Revo.
Good Luck gettin that fixed buddy!