I bought my 2002 3.0l DT 4 weeks ago, 250000KLMS. Now It has just started emitting a high pitch whine when I hit 95 klm hr. , this noise seems to be coming from front RH .It stops as soon as I take foot of accelerator and starts again as soon as I put it on again. Is this a sign my diff is on the way out , or what else could it be ? hopefully something less expensive??? your thoughts please...