Used them many years ago to have a transmission in my ford ranger fixed, and while it was more costly than any other shop the repair was well worth it as when I sold the truck several years ago the transmission was still going strong. And they do have a nationwide warranty coverage.
Really nice people in Clayton. Never had transmission work done. I don't remember what they did, something like brakes or ball joint maybe? I just remember I was satisfied with the work. I've checked them a few times for other things, but went somewhere cheaper.
Mike's Transmissions I have not had work done at AAMCO, but I recommend Mike's Transmissions in Durham for good price and good work.