[boots4]

I really like what I've read about the 4L80. If you are going to run big power and that 700r4 is just stock I would lean towards the 4L80 but I know the decision isn't as simple as that.

Stuff you might know: to operate the 4L80 you will need a controller, either aftermarket or the computer that you got that combo out of. What I've read is it's easier to set up an aftermarket controller rather than trying to get the factory stuff to work right. Then there are the sensors like the VSS that you probably don't have since the 700r4 isn't electronically controlled. Plus the 4L80 is bigger and tranny mounts might not line up. The flywheel flex plate also has a different bolt pattern than the 700r4 so if you plan to slap the new engine and the 700r4 together that will have to be dealt with. You will probably get more money out of the 4L80 if you sell it, thus funding other projects.

I choose the 4L80 over the 700r4 mostly because I'm running a diesel and wanted the extra strength. The lower first gear ratio didn't matter to me because of the torque curve of this diesel. Sounds like a good decision to wrestle with.