01 Tahoe Rear End Whine

[Bedore]

It seems to only whine when I am cruising around 60mph...and I left off the gas to coast. Once I get back on the throttle, it stop's whining. I will try a rear diff fluid change. Anyone know how much fluid it holds? Also I think I have a limited slip rear end...don't I need to add something to the fluid?

 

[THOLL223]

Could it be the U joint? When mine was going it would whine until I let off on the gas, the sound would go away. Replaced the U joints and it went away.