To be certain:
* Visual Inspection: Look closely around the thermostat housing and the cylinder head. The sending unit will be a threaded sensor with one or two wires attached. It might be slightly recessed into the cylinder head.
* Consult a Repair Manual: A repair manual specific to your 1997 Dodge Ram 318 will show the exact location with a diagram. This is the most reliable method.
* Online Resources: Search online for "1997 Dodge Ram 318 engine temperature sensor location" along with images. Compare the images you find to your engine.
Caution: Be careful when working near hot engine components. Allow the engine to cool completely before attempting any inspection or repair.