To be absolutely certain, you should:
* Consult your owner's manual: This is the best source for the exact location in your specific vehicle.
* Check online repair manuals: Sites like Chilton or Haynes offer detailed diagrams and information for your year and model.
* Use a vehicle-specific online database: Some websites allow you to enter your VIN to get precise diagrams and part locations.
Searching online for "[Your Year] Dodge Ram 2500 PCM location" will also likely yield helpful results, including images. Be aware that the visual appearance of the PCM may differ slightly depending on the year.