There is water in the oil, and the car overheated and blew a head gasket.
I wouldn’t condemn the head gaskets just yet. Intake manifold gaskets are a common failure item on your Chevy's engine. When they fail, they can leak externally, or internally, or both. When they leak internally, coolant gets into the oil. The resultant low coolant condition can cause overheating. Coolant in the oil will degrade the engine bearings very quickly; do not drive the car like this. Some indicators of head gasket failure are: heavy white smoke out of the exhaust, rough idle, engine running poorly, or consistent air bubbles in the radiator. I recommend having a top-rated mechanic, such as one from YourMechanic, come out to your truck's location to run a diagnostic inspection of your overheating issue, and suggest the best path to repair.
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