One problem related to water pump has been reported for the 2004 Chevrolet 1500. The most recently reported issues are listed below.
Noticed coolant level would get low. Found water pump mounting gasket leaking, replaced water pump and gaskets, but continued lossing coolant. Found out there is a know defect with chevy 4. 8 and 5. 3 vortex engine heads cracking around the mounting bolt holes. Chevy issued a TSB but will not warranty a know defect. It strange they will cover a hvac blower motor issue that is know but not a known problem with heads cracking without any fault of the owner.