Have the trans computer checked for codes, there could be a failed governor sensor.
I had a problem like this recently. Mine would do that if I sat at a stop under normal conditions and then started to move off and then change gears erratically. I found that when I put it ion neutral and reved the engine to about 1100 it would not do that. So I replaced the Alternator Figuring I had AC on the system like a shorted Diode and it replacing the Alternator fixed the problem...Note: I at first took the Alternator to a generator shop where the actually rebuild them and after opening it up and giving a good look the specialist said that there was too much wrong to be worth his while to rebuild. I used it for a core at one of the local auto parts shops
47RE
A518
A518 is the transmission if it is an automatic, and if it is a manual then it is a Getrag 360.
It is a completely different transmission than what was used with the diesel before.
Chrysler/Dodge does
The automatic is a 47 RE. The manual is a NV4500.
The manual is called a G56. The automatic is called 48RE.
Mopar ATF+4
The automatic is a 47RE. The manual is a NV4500.
Stock an automatic is 195 hp a manual is 215 hp.
The automatic is called a 47 RE. The manual is called a NV 4500.
Mopar ATF+4