I have had three previous chrysler minivans with the A604 transmission that everyone complains about, but mine have all been virtually trouble free. The first was a 90 Voyager SE, and needed a complete flush with the correct fluid, but then worked fine for 90,000 miles. I got it with 125,000, and don't know if it was replaced before I got it. Used it to carry lawn maintenance equipment (small mower, weed whacker, etc.) It started to "bump down" at about 215,000, and it was so ugly by then I decided to scrap it. I got the $300 that I paid for it back at the scrap yard!
My second, a 90 Caravan, had 165,000 when I bought it... also for $350 (both had bad water pumps when I bought them), and drove it up to 195,000 with no transmission problems at all. I did flush it with ATF+4 and put a cooler on it when I got it. It also was scrapped after two years with other numerous issues, and I had already bought a 90 Voyager LE, so I swapped the best stuff to that and scrapped the Caravan.
The Voyager LE had 168,000, also with the A604. I put the cooler on it, and drove it up to 195,000 with perfect transmission performance. I just scrapped it because it needed a LOT of stuff... Water pump, brakes all around, CV axles, Wheel bearings to name a few.
Anyway... I bought a 92 Caravan SE last week that is in pristine condition inside, has a new trans, and a bunch of other new parts, good tires, all new brakes, recent timing belt/water pump, etc. The AC works, which none of the three previous ones did. I paid $1,150. It needs valve guide seals, which I am getting pretty good at after doing three other vans, and will need shocks soon. The one thing I did not even consider was that it might NOT have the A604. It is the A670, and I just checked the mileage and it is awful. I got 16 around town (DC metro area)! I was getting 24 on the highway and 19 or 20 around town with the overdrive.
Finally to my question... Am I an idiot to want the A604? Can I put it in this one? I don't see a trans computer in this one, so don't know how hard it would be to upgrade to the electronic trans. Or should I just buy another van? All the articles I have seen so far are about swapping the other way... I want my extra 60 or more miles per tankful! I may be able to clean the throttle body, and some other stuff to get it up a little, but I doubt it will go as high as the overdrive did.
This van has 175,000 on it, with 25,000 since trans was overhauled.
Hope you guys can help me with this decision. Thanks!