Ok guys this is what I have; I picked this truck up at an auction a few weeks ago, it has 156,000 miles on it but it runs great. I'm noticing an antifreeze smell from under the hood & I can't seem to find any visable leaks. It does have the red coolant in it, here's the list of stuff I looked at trying to figure this out: Starts and warms up fine (stays just under 210), heater works fine too. Pass floor dry No apparent antifreeze smell in exhaust Oil looks normal (oil pressure is at 40 at idle) I've read that the 2001 - 2006 5.3's have head problems but considering mine's a 1999 I don't think this is the issue (at least I hope not). Any thoughts?