I didn't read the whole thread, but I just put a beefed up 700R4 in mine. I'm running 2500 @ 65 (SBC) with the ol' 6.17's. I'm happy. I also want to update wheels and tires, but, in due time. You can also go with GMs beefier transmission.. 4L80E but it requires a computer to handle shifting. They have kits. I opted for the weaker transmission, and just had a really pro build on it. My truck is 6K empty, but like you I never carry a load. Seems to be fine and runs cool (tranny).
