Where is thermostat on 2004 Chevy Tahoe?

Follow the upper radiator hose to the intake manifold. That is the thermostat housing. Unbolt the two bolts to change it out. Just remember to drain the coolant/ antifreeze first.

It absolutely depends on which engine you have which I didn't see posted. I've a 99 5.3 and it's thermostat is NOT on the intake.