what would cause the rear end of my 2004 Mountaineer to whine during acceleration?

Question

The whining noise is heard at speed of 55 and above when i get off the accelerator the noise stops, i just put new tire on factory spec, so I know that is not the problem.

Answer 1

Axle gears are not meshing properly--have to pull the cover and inspect the wear patterns on the teeth of the ring and pinion gears and reshim as necessary....dealer or axle shop can do. Under warranty?