It's very simple and you'll come out ahead by selling the T56 and going to a 4L80. You'll need the flex plate, converter, a new harness from PSI for simplicity's sake, and you get to retain the Regal pedal assembly which makes your life easy. Then you'll need to have your computer reflashed. There's really nothing to it.
Sell the T56 for $1,000-1,500 and pick up an 80e for $300 or so. There are differences in the production years of the 80's, but all should be pretty stout. More so than the 60e at least...
Can you be more specific about what you're wanting to do? You have a regal and are going to ls swap it but the ls1 has a t56 and your want to do an auto instead?
Can you be more specific about what you're wanting to do? You have a regal and are going to ls swap it but the ls1 has a t56 and your want to do an auto instead?