Non-Axle Noise

There are several components, which when subject to certain conditions, can produce sound similar to axle noise. These components are the exhaust, the tires, roof racks, the power steering pump, auxiliary fluid coolers and the trim moldings.
^ The pitch of the exhaust can sound like gear whine.
^ Tires - especially snow tires - can have a high-pitched tread whine or roar similar to gear noise. Radial tires, to some degree, have this characteristic. Any non-standard tire with an unusual tread construction may also emit a roar or whine-type noise.
^ Trim, grille, and moldings can also cause whistling or whining noises.

Make sure that none of these are the cause of the noise before proceeding with axle teardown and diagnosis.