My go to for this kind of thing is to find a low-mileage used unit from a T-boned or rear-ended truck. You have four basic options:
1) buy a reman and put it in yourself. Usually a pretty good gig, but if there is anything wrong with it, you're stuck doing your own labor twice
2) take it to a shop where they can pull and rebuild and put it back in. This is where shop quality seriously needs to be addressed. A good shop (like mine were) will fix what's wrong instead of just saying "yeah, it totally needs a $5000 rebuild." It's entirely possible that you need a solenoid, a valve body, or an accumulator spring instead of a whole new thing.
3) Dealer, but dealers don't crack open transmissions. If you have a bad neutral safety switch, they will likely suggest an entire new transmission. They'll get one brand new from Ford, mark it up 200%, and charge you high-end labor. Dealers are the last place to go for transmissions. We had an Audi R8 in our little cut-rate shop because the dealer said it needed a new transmission for $16,000. One quick google search showed me that the problem was the internal PCM was fried and verified that with a simple procedure with a multimeter. New PCM from Germany for $600 and $500 worth of labor, programming, and unicorn-pee ATF, and he was back on the road.
4) Buy a used, low-mileage unit and put it in. Again, if it's f'd up, you're stuck doing the labor twice, but here is why this is my favorite option.
Ford builds their transmissions in a place that has millions of dollars of dynos, computers, dust-free air handlers, and it is operated by hundreds of highly-trained employees whose job is strictly assembling one or two parts of a 6R80 using laser-guided assembly equipment that looks like this:
A rebuild shop has one person who may or may not have ever built a 6R80, and has a jack-of-all-trades approach to rebuilding. They may also have limited knowledge of what commonly fails, how the electronics work, or the ins-and-outs of what makes them tick. They just spent all week working on two A320s, an RE55FE, three 700r4s, one Allison, and five 47RE units. They also have a bench that looks like this:
For this reason, my preference is to get a low mileage used trans. I would rather have a 60k-mile box that was built by the people in the video, than a zero-mile reman from Jim-bob's bench o' questions.
Having said that.... if you find a quality rebuilder, it can be a good way to go. The warranty and all the labor for R&R is covered by the first round. If they don't get it right, they'll pull it and fix it on their dime.
Perhaps you could find a neighborhood kid who wants to help out for beer/weed money? Lighten the load?
