So.... After using sheet metal screws, shimming the pinion, etc... My factory diff case finally blew out on my Chimera. Only one solution 7075rc diff case. As always, great craftsmanship. These diffs don't have a relief at the bottom to accept the rear bumper. This has always been a weak part, as I've cracked the upper brace countless times. I decided to buy some flat stick Delrin (acetal plastic) and build my own. Scroll saw, grinder, and torch is all it took. It's bulletproof, how do I know? Smashed it countless times jumping. This plastic is indestructible, however playable enough where it still absorbs shock.