MY EXPEDITION HAVE A NOISE IN A REAR DIFFERENTIAL ITS LIKE WHEN THE TRUCK GOT WARN

I would have to drive the vehicle to experience the noise and to do some componet checking.

My 97 used to make a wheel slip sound turning left or right,took to local lube shop-still did same thing.Took to a real mechanic,used a special rearend lube,been working perfect 20,000 miles later.Truck now has 231,000 miles.