coolant boiling out of overflow

well as ive stated before on another thread, ive got problems. Today i took the truck out for a test run with barsstop leak in the system. when i got home (maybe 30 minute drive) i could hear coolant boiling under the hood. Popped it and voila, coolant was belching out of the overflow. Now, i have no white smoke, so is it fair to say that it is the head gasket still? I'm too green to know the difference. My gut tells me its something much worse. ANy help? Raul

Yuppers. U've blown the head gasket, and at all worse, the head itself is cracked. U dont need white smoke to do this.
Ok, the first test is, run the engine for a short amount of time, does the coolant piss out, and is it COLD or HOT, if its cold, its the head or head gasket. Next, use a cooling system pressure tester and put the cooling system under pressure. Before this though remove all the sparkplugs. Keep the system at pressure for 5 min or so and then have someone crank the engine while u watch the sparkplug holes. Does coolant come out one of them??? If so pull the head and inspect the head gasket on the cylender(s) which sprayed coolant. Then inspect the head for cracks. If the head gasket is broken somewhere then obiously u just need a new one.