Sqeak in Reverse ('02 Yukon XL)

[07radoman]

Greetings all,
My '02 Yukon XL sqeaks when in reverse gear. The problem does not happen when in drive, or when you are in neutral rolling backwards. It only happens in gear and in reverse. I have heard this could be u-joints or brake, but assume if brakes were invovled I would hear it when the vehicle was rolling irrespective of whether it was in reverse or not?

Any information would be greatly appreciated.

Thanks - MIke