I recently purchased a 2002 Yukon Denali. I've noticed a whining sound from the front end when I'm at a steady speed. When I take my foot off the pedal, the sound stops. I had it in the dealership and they first thought it was the front drive shaft and replaced it. That didn't help at all, so they then told me it was due to the all wheel drive. Does anyone else have this problem, or do you have any ideas as to what is causing this?