2003 Chevy Truck Leaking Antifreeze

Engine Cooling problem
2003 Chevy Truck V8 Four Wheel Drive Automatic 150K miles

I have to keep adding antifreeze about once a week, roughly a half gallon or more at a time. I cannot see anywhere where the antifreeze is leaking from. I recently replaced the water pump and thermostat along with gaskets because the water pump gasket was leaking. Ive checked my oil and see nothing in it (no icecream). Could it possibly be a bad head gasket or bad intake gasket? The truck isnt missing any so I didnt think it would be a cracked head.