* 47RE: A four-speed automatic transmission. This was a very popular choice.
* NV4500: A five-speed manual transmission. Also quite common.
* Getrag 360: A five-speed manual transmission, less common than the NV4500 but still possible.
To know for sure which transmission is in a specific 1997 Dodge 2500 diesel, you need to check the vehicle's documentation (like the owner's manual or build sheet) or look at the transmission itself for identification markings.