I have a 2002 F150 with the small V8, auto trans, with a little over 100K miles. My VIN indicates that I have a limited-slip rear end. (2 wheel drive) For the last several years I have heard a slight whine which shows up at 35 to 45 MPH, then again at around 70 to 80 MPH. It is not related to engine speed, as I can put the tranny in neutral and still hear it at those speeds. The noise seems that it may be coming from the rear of the vehicle, but I can't tell for sure. Nor can I say with any certainty if it is coming from the right or left side. The hum or whine seems to have gotten a little more pronounced over time. It is not loud enough to hear it with the windows open. I thought that I might raise the wheels and check various locations on the rear axle with a stethescope with the engine running, truck in gear, but someone told me that the anti-lock breaks would activate since the front wheels would not be turning. I sure could use some advice. Thanks