Everybody has some very good suggestions and idea, however I have done 99% of the items listed and to no avail. There is some minor exhaust white smoke when it first starts up, but then goes away when warm. I truly dont think there is any external leaking, but I will get that radiator pressure tester and verify. Like I have said in the past, I have replaced the water pump, radiator, thermostat and now the intake manifold gasket. There was nothing wrong with the old intake manifold gasket, but all my symptoms led to changing it. I hate changing things that really didnt need it. I believe I am somehow leaking coolant into the engine by whatever way is possible because this is why I am starting to get that lifter tapping after about 1000 miles after an oil change.
By the way, does anyone know how hard it is to remove the oil pan on this 4X4 vortec V-6? I understand I have to remove the 4X4 section to get at the oil pan. I want to check for sludge build up on the screen and inside the pan. I know it has some build up because when I change the oil, the very last few drops of oil are not really drops, more like liquid mud. Thanks for all your help, Randy