Where is the thermostat located on a 2003 GMC Savana 2500 6.0L engine?
Inside the thermostat housing...the housing is bolted directly
to the water pump on the lower left side with 2 hex bolts(10mm).
The outlet of the therm housing connects to the lower rad hose. You
should the able to remove the top hex bolt simply by reaching over
the fan shroud and down behind the serpentine belt. The lower bolt
is easier to remove from underneath the van.