I had a boom once, it was the clutch. It was all over the place under the car. It looked kind of like hay comeing out of the inspection cover.... It would not go into gear b/c it just wont with out the clutch. I havn't blown a tranny like that before so I wouldn't know. Hope I never do!!
We pulled the tranny out tonight. The output shaft was broke, actually, it looked almost like it was laser cut. Snapped real good.
So, until I can save up for a tranny that'll handle 540 ft/lbs. at the wheels, I'm slapping a used 4 cylinder T-5 in there just to get around town, transport, etc.
Just because you make 600 Tq at the flywheel doesn't mean you're able to plant that to the ground. Use the torque ratings of the various trannys as a guide, not the 'end all' is whether it will stand the test of your combo.
Consider how long your current tranny has lasted you and it's torque rating.