[bwood]

Intake gaskets are notorious for failure on the 96-up 4.3/5.0/5.7 engines. The symptoms are exactly what you describe. Sometimes the leak is on the outside and runs down the rear of the passenger side head or down the front of the drivers side head. Most of the time, the leak is internal and leaks into the oil through the lifter valley and can kill the engine if not caught soon enough. Leaking into the cylinders can also happen. I would guess that the majority of the gasket failure was on the passenger side near the back above cylinders #6 & #8. Clean up the lifter valley the best you can and change the oil when your done. Any remaining moisture in the engine should boil off when the engine gets warmed up good. Use the Fel-Pro MS98000T intake gasket set, it costs a little more, but if installed correctly you should never have this issue again. There is a specific bolt torque on the 8 intake bolts, and its not very much. If you still want to rule out the head gaskets, do a leak down test on each cylinder.