This is probably misconstruing the ATF+ requirement starting with the Ultradrive electronic transmissions. Prior to that Chysler was all Dexron. Sometime in the early 90s the new electronically controlled Chrysler transaxles began using a different friction material in the clutches which required the "+" fluid. Some shops took to using Dexron with Lubeguard Black as a substitute, even some dealers because that was all they had in stock. You could tell which ones they were by the number of minivans parked in the lot out back. It didn't work very well.
