Is MT "Monster Transmission"? If so you clearly didn't do your research.
http://www.ckperformance.com/List/2004R/2004R-Transmissions
I am going with the 400 unless things change. Yes I bought it from MT. It was nothing but trouble.what about putting in a th350 for now to get the car mobile again and that'll give you some time to figure out what to do with the 200 4R