I swapped at t56 from a GTO into my 2000 silverado 6.0. Still running good, I believe I added a lot of info in my build thread on the swap. I use to have a 4l60e as well, my decision was either go to 80e or manual transmission. I chose manual because I do not do a lot of straight up strip racing where a auto would be preferred. Like above it just depends on what you want out of the vehicle.

 

If you want car like performance a T56 or TR6060 is about your only option. What part of AR are ya in?