* 3.9L V6: This was a relatively common engine option.
* 5.2L V8: A more powerful option.
* 5.9L V8: The largest engine typically available.
To know for certain which engine was in a *specific* 1988 Dodge Ram 150, you would need to check the vehicle's documentation (like the owner's manual or a vehicle history report) or look for the engine code stamped on the engine itself.