i had the same problem with the u joints and thay didnt whine thay just broke had to get a new shaft to get rolling again

 

pinion bearings have been known to whine as well however without changing the angle of torque with a lift I dont see it being remotely possible, still think you should check the carrier, and if its a diff problem i wouldnt wait for it to break something before i got it warrantied, dodge diffs have been known to run another 30,000 miles before they finally suffer failure do to an existing problem