I have to say to me it sounding more like a rear wheel bearing and hub assembly..I changed mine a couple of weeks ago, my rear end at low speed was making all sorts of noises...For some reason the rear hub assemblies are made of soft metal I pressed it on only turning the wheel on the press..Mine was the L/h rear and the cv shaft was completely dry I think ford forgot to put lube on it..Covered in some sort of rusty dust..