I would check the fluid level first, then I would see if the driveshaft is spinning while in gear when stopped this would mean you have a broken rear axle which are common on these trucks. Here is a guide to help you with the transmission fluid level check.
https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid
Fluid Types
Transmission Fluid Type
Type .................... MOPAR ATF +4 Type 9602 or Equivalent
Capacities
Transmission Fluid
42/44RE .................... 9.1-9.5L (9.6-10.0 Qt)
45RFE .................... 13.33 L (14 Qt)
Please let us know what happens.
Thursday, October 10th, 2024 AT 5:40 PM