90s 3.9 v6
I'm not sure if the switch to RE coincided with the sw to Magnum, but likely it did.
The switch to the 42RE transmissions, from what was originally the 42RH (aka the A500), coincided with OBD2. So generally speaking, 1995 and back was the RH, 1996 forward was the RE.
For the OP, in case you're not familiar with them terminology when we talk about 42RH / 42RE:
4 - Number of forward gears
2 - Strength level (2 = kinda low, 4 a bit better, 6 even better, 7 or 8 you're into V10 or Cummins trans territory)
R - Rear wheel drive
H - H for hydraulically controlled, E for electronically controlled.
You can identify whether it's an RH or RE trans by looking at the connector on the driver's side of the trans, above the neutral safety switch connector. The most desirable hydraulic transmissions will have 3 pins; 1 for power, one for torque converter lockup, and one for the overdrive shift. The less desirable transmissions don't have a lockup converter so they will just have 2 pins; 1 for power and another for the overdrive shift. The RE transmissions will have an 8 pin connector. If you get one of these you you have to run the OBD2 computer or some other electronic controller/
