Here is the Skinner on Chrysler ATF (automatic transmission fluid). The ATF was the base type of transmission fluid on Chrysler/Dodge units. Around 1984, Chrysler had a problem with their lock up torque converters slipping when engaging. They used an additive to stop this. It changed the ATF to ATF1. A few years later they had a problem with the electronic controlled A- 604 so they added another product to the ATF1 and that changed it to ATF2. As time went by, they encountered other problems in the 604 (now known as the 41 TE transmission). And finally we have the ATF4, which is the latest and greatest of all ATF's. To my knowledge one can use the ATF4 in all Chrysler transmissions present and past. But you aren't suppose to use Dextron or plain ATF in any that specifies ATF1, ATF2, ATF3, or ATF4 because it doesn't have all the additives for that transmission.
Chrysler Master tech Retired.