Well, this tranny has only been hooked to the 500 for about 1200 - 1500 miles, and to the 425 for less than 200 miles.
Plus, the converter is out of a TH400, so the age of the converter is a moot point as far as the tranny age is concenred.
I have yet to tow anything, haven't hauled more than 1200 pounds, and in all reality, I don't rag on it too much. Granted, i have gotten into the throttle a few times, but nothing REAL severe.