* 4-speed automatic (46RH/47RE): This was a very common transmission for many engine options. The 47RE was a more refined version of the 46RH.
* 5-speed manual (NV3500): Available with certain engine choices.
To know for sure which transmission is in a specific 2001 Dodge Ram 1500, you need to check the vehicle's identification number (VIN) or look under the hood at the transmission itself (often a sticker or casting on the transmission case will identify it).