As some of you know I was having an overheating issue with the Crockpot. I had assumed that the problem was the head gasket but alas it is not! Well, at least I'm pretty sure it's not. Symptoms were overheating at highway speeds, no visible leaks, no milkshake, no visible oil in coolant but coolant turned dark after first overheat and one cylinder down on compression. I spent some time with the rig over the last few days...adjusted the valves, performed a flush and changed the thermostat to OEM. I believe the non-factory thermostat must have been sticking, although it passed the boiling water test. The rig seems to be holding temperature very well now and the latest compression test confirms the valve adjustment brought the bad cylinder back in line with the others. Truck is running pretty good at the moment. Today is the third day I've driven it to work this week and not a single issue. Thanks to everyone who offered advice. I really appreciate y'all!