On the 2003 with the V8 the "temp sending unit" is the "Cylinder Head Temperature Sensor". With the hood open, if you were to stand on the driver's side fender and look at the engine, the connector for it is located just above the upper left of the valve cover. The sensor has a pigtail on it. It will have two wires to it, a Yellow/Light Blue wire (reference voltage) and a Gray/Red wire (signal return).

It sounds like you're fishing for an issue. Care to share some details on the symptoms?

-Rod