I have an 01 2500HD with the 6.0L, and ever since I bought this truck, it has made an awful squeaking noise as I was coasting with no brakes applied. I figured it had to be somewhere along the driveshaft since it only squeaked while the truck was rolling, turned out I was right. I looked at the drive shaft and the first thing I noticed was that the hangar bearing needed replacing. Ever since I replaced it, she's been running smooth and quiet.

 

Wow Good eye on catching that one. It definitely needed replacing