The 604's that Chrys. used were a real winner. How many fires have you heard of on front wheel drive Chryslers? I hear them all the time. Most of the time it is transmission problems that caused it. I have worked on them for a lot of years. About half that came in for repairs were not even trans. related. If the engine temp. got to high, battery voltage too low, or other simular problems then it would put the transmission into limp mode, 2nd gear only. Disconnect the battery for a few minutes and all well again. You could be sitting and listening to the radio with the engine off, start the engine to drive off and your in 2nd. Also with those transmissions were you should drive with OD out. They would get hot if you didn't.
The problem with them after being rebuilt is that most rebuilders or R&R guys do not replace the input speed sensor and turbine speed sensor. When these transmissions go out, they dump a lot of metal. Both sensors are magnits and the must be replaced. Most rebuilders just clean them off. Well cleaning does not work most of the time. I have seen rebuilders replace the silonoid block, and transmission computer and it still would not work. I have seen transmissions get rebuilt because of those two sensors needed replaced.
These transmissions would work good it you keeped them serviced, and driven the correct way. The worst auto transmission ever is the ECAT used in 89 Mazda's 626 and Ford's Probe. These transmissions were the worst POS ever. They went out early and at first they were not rebuildable. There was a rubber line that made a very sharp 180 degree turn that would always leak or get kinked.