there is nothing wrong with the losi rear diffs, iv read over n over on so many threads how u keep on going n going about the losi diffs. shim it correct and you won't have problems. I don't want to sound rude and by no means am I trying to be rude but iv driven my practice truggy for years now and I haven't had to ever use my spare diff n pinion. Literally I have rust on my gears from years of cleaning with water and still no issues. The biggest thing is you have to start fresh with new parts, shim it correctly and u won't have issues. If your using new parts and your going threw diffs in 20 minutes of your first run you cannot possibly be building it right, period! Maybe u should have someone else build it, hell send me your diff and the housing and the pinion and ill build it and send it back to you. The buggy diffs in your truggy is not ideal for gearing it just isn't right your losing performance.