Tranny question?

I am in the midst of a poncho 400 build up. Final specs will be 500 hp and 525 tq. I need a real strong tranny to back this up. What would be the strongest factory tranny that will fit this engine? Any info or tips would be greatly appreciated. Thanks.

Auto or manual??
The Super T 10 found in many Firebirds will not handle this in stock form. IMHO the Muncie 'rock crusher' found in Camaros is a bit stronger.

I would suggest a THM 400, though. They can be built to cope with this reliably.

yeah i forgot to speficy. Manual all the way.