2004 Mercury Mountaineer, growling sound from rear when accelerating from a dead stop, also AWB light on and off, found other problems reported, solution was to change differential oil and noise stopped light went out, so they say, it has been at my mechanic all day and he can find nothing, thinks it is in rear diff clutches or gears or setup, not equipped to do it, again I have been advised to have the diff oil changed to a heavier synthetic oil,