Draining coolant

Drained the coolant from my Buick Rendezvous and only got one gallon out of the bottom of the radiator. The book says it holds two gallons. Don't see any drain plugs in the block. Any ideas, I was thinking of pulling the bottom hose to see if that would give me any more.

If the buick you have has the 3.1 V6 in it, bleeding the system can be a problem with the thermostat being in the side of the intake. Make sure you bleed the system good other wise you will have over heating problems. I would take the bottom hose off of the radiator and buy a radiator flush kit to put in the heater hose line. The other gallon of antifreeze is in the engine, heater core, and overflow tank.