[Hank70SS]

Are you interested in a manual or auto? For a manual the Muncie M22 4sp is what they put behind the 454 from the factory. They're pretty tough transmissions and will hold up. An Muncie M20 or M21 4sp will also hold up unless you have a lot of traction and really want to beat on it. The M20 and M21 are the same transmissions with different gear ratios. The M22 is stronger, same gear ratios as the the M21.

For a 5 or 6sp there is the Tremac. The 6sp costs a little more but requires less cutting of the tunnel. Ric, (RBeckman) installed a 5sp last winter. You could PM him and get his thoughts. I know he wishes he had paid the extra for the 6sp so he wouldn't have to do as much mods to the tunnel but he does like the 5sp now that it's installed.

For an auto the TH450 as mentioned is a tough trans. The 700R4, 4sp, is also a good trans plus you get the overdrive. Can't help much more with auto's. Either way unless you know what you're doing you may want to look for a good rebuilt.