That's the thing about an automatic transmission. Nobody is perfect. One cut seal, cut ring, bad part, anything like that can cause problems. There are so many variables in making them work right. Every transmission man has comebacks. It's part of the business. We have a transmission in the shop now that's a AOD out of a mustang that came from a huge internet site. They are good people and built a good transmission, other than one cut o-ring. They are paying the repair bill, sending the parts down, but its a hassle for the customer. I always tell people to find someone local. Ask around, find someone you can trust. Most of the transmission shop site's are good marketers. When it boils down to it, a 700r4 or 4L60E is not hard to build. Most reputable shops use the same parts, every builder has his own little (tricks). Installation is another variable, stacked pumps and cables not adjusted correct is a nightmare.