So why did you trade it on a foreskinner? A '99 Durango would have had an A-518 transmission, which is based on the A-727 that debuted in 1956. Its a most thoroughly debugged transmission, reliable as gravity, and not at all prone to the kinds of problems minivan transmissions are. You took a financial bath bath on a vehicle that probably had 200k miles left in it (and even if it didn't that transmission is cheap to fix) and traded it in on an inferior vehicle, IMO.
But even the "bad" ones are better than the import-o-philes would have you believe. I bought an Eagle Vision (Dodge Intrepid) in 1993. At
150,000 miles, the transmission was leaking from an O-ring that required removing the transmission to replace so I had it rebuilt even though it was still working fine. The car has 209,000 miles on it without any other major repairs, still going strong.My '73 Plymouth is still in daily use at 432,000 miles, and my '66 Dodge made it to >260,000 miles, and will go on much further once I finish rebuilding its engine (which still RUNS fine, but down on power).
In contrast, I've never nursed an Asian-built car past 150k without it suffering massive multiple organ failure- like the whole front suspension falling apart on a Mazda.