First off I'm new here and will admit I'm totally retarded when it comes to all this programming stuff so forgive me if this is a dumb question or one with an obvious answer, I searched all over and havent found the answer yet. And this seems like the place that might finally be able to answer it.

So the short version is I have a 454 that had a 4l80e behind it both out of a 91 chevy 1 ton dually. If I swapped out the 4l80e for a 700r4 or a th400 what would happen? Would it start running wrong in anyway and need something reprogrammed to fix it? Or would there be no issues?

Now the longer version in case you need some other info.

I have a 77 chevy k20 that I just pulled the 350 out of and replaced it with a tbi 454 out of a 91 chevy 1 ton. I had the whole 91 chevy to work with and pulled the motor and tranny, complete wiring harness both motor side and from under the dash, all fuel lines and both gas tanks, and the radiator, plus some other random thing just in case. I've got the motor in and ready to go now the transmission is my issue. The donor truck was a 4x2 with a 4l80e. I know you can change the 2wd 4l80e to 4wd and put a transfercase on but I'd rather not deal with the hassle or the extra cash to do so. I have on hand a th350, th400 and a 700r4 all with transfer cases and in good shape ready to go. what if anything needs changed to make one of them work? I know they all bolt up but dont know what issues it is going to cause switching from the electronic 4l80e to a non electronic transmission or what needs done to make it work. The truck will be mostly offroad only when this is all done if that makes a diffrence.

Any advice or input is appreciated. Remember I'm a noob and know basically nothing about programing anything. I'm pretty sure I know what the PCM looks like but that would be about it. Im good with older engine stuff but all the electronic stuff not at all. Im willing to put it the work and time to learn just point me in the right direction.