Wow! Thanks for all your advice. After reading Donn's clicky I think I'm back to square one. I talked to one of the guys in my dealers parts dept. He had his air intake system swapped out for the '06 system, but it did not completely correct the heating problem. The more people I talk to, and the more I read, the more confused and angry at GM I get. I see that some of you have made modifications in your radiator/cooling sytems but I'm not handy enough to do that work myself and I don't know of anyone in the area who does it. Guess I'll keep up the research. Thanks again.