The oil pressure sending unit on a Dodge 5.2L V8 engine (commonly found in older Rams and other vehicles) is located on the
driver's side (left) of the engine block, near the front. It's usually a relatively small unit with a single wire connector. It's important to note that it is *not* typically on the oil filter housing.
Because the exact location can vary slightly depending on the year and specific model of the vehicle, it's best to consult a repair manual specific to your Dodge's year and model. A visual inspection with the engine bay clean will also help you locate it more easily.