GTO transmission

my freind just got a 1970 GTO with a 400, he wants to swap the tranny for somethin aftermarkey, somethin bigger wit better gear ratios and wut not, if anyone knows anywhere he can find transmissons for his goat it would be greatly appreciated

Now I'm confused. I can't remember whether the later goats came with the 400CI smallblock, or the rat motor that got enlarged to 400CI. I remember they put 400CI big blocks in chevies, but kept the 396 badging just for the name.

B&M makes good trannies. Get a TH400...