rsavage,
It sounds to me that indeed, your radiator is 'toast'! If your truck started steaming, even without a thermostat, there was a root cause. Aside from improper timing, a long pull up a steep hill on a hot day, or a plugged block (rare), the usual culprit is a old plugged radiator.
Proper engine cooling is the foundation of the entire system. As was mentioned above, a new radiator, or a re-core, is the solution to this problem.
Stuart
