RE: Water Temp Sending Unit
it should be located right behind the alternator and to the left of the uper radiator hose (as your looking at the nose of the truck) and its screwed into the intake plenum,,, has a wire harnes thats a PINTA to get to but you can get it off very carefully with a set of needle nose. release the built up pressure in the coolant system and motor by taking off the radiator cap then unscrew it so your not showered with coolant. Thats where its at on my 01 5.9 should be much different. you getting a messed up reading on your temp gauge? and youre actually looking for the ECT sensor witch is the Engine Coolant Temp sensor. goodluck! i had a heck of a time troubleshooting this problem.. need any hlpe lemme know!