I build a lot of these transmission's and there damn strong, but depending how your launching, the weak point will eventually go, and it aint going to be the rear end normally! are you using a 2 step or just dumping it to the clutch? One old school trick I have done for years is tapering the ends of the slider shoes, and hardening them as mentioned above, this is probably the weakest part of the gear box, and it will normally be the part that blows apart first. And I applaud you for running a stick car even with the technology out the with the automatic's, nothing better then banging gear's like Ronnie Sox, and Dick Landy used too!!!!
