I have an '04.5 (LLY) Duramax 3500 w/ the 6-Sp. and 133,000 miles. I have a high pitched whine that kind of sounds like the bearings in the turbo. I have had it in the dealer a couple of times and they say it's not the turbo but their not sure what it is. It has been doing this now for probably 25-30,000 miles. It does not seem to affect the way it runs although my fuel mileage has gone down some. My truck is completey stock and I do a lot of heavy pulling with it. I have checked the intercooler hoses and everything seems to be intact.

Any ideas?