My BIL picked up an 04 yesterday with 144k miles. Zero blowby when removing the oil filter cap. First problem there is a coolant leak at the GP on the passenger side. Only leaks when sitting cold and isn't enough to make a spot on the driveway. The leak goes away while the engine is running. I told him at the worst case he needs a new head, and while in there he should bulletproof the engine engine. Prior to going that far, is there an o-ring or anything that can be checked? I've never worked on a 6.0 but have two 7.3s sitting in my driveway.