So you bought the transmission from one guy and it wasn't right from the time you put it in, so you had another guy fix it and it made it 40 miles. The place you bought it from is in the clear because you had someone else work on it. The second guy, that rebuilt it, is on the hook. His rebuild made it 40-60 miles, yup, he's definitely on the hook.
I'm a little confused on your description of 'the shaft broke' and the driveshaft was so tight that he needed a ry bar to get the driveshaft out. What shaft broke? And did you get the driveshaft shortened? Sounds like the output shaft was loaded due to an overlength driveshaft, if that's the case, then that will break every transmission out there. Have you pulled the driveshaft since the second/third failure?
I'm a little confused on your description of 'the shaft broke' and the driveshaft was so tight that he needed a ry bar to get the driveshaft out. What shaft broke? And did you get the driveshaft shortened? Sounds like the output shaft was loaded due to an overlength driveshaft, if that's the case, then that will break every transmission out there. Have you pulled the driveshaft since the second/third failure?