For 1990-2009 cars

Differential side bearing noise is easily confused with wheel bearing noise. Since side bearings are preloaded, the noise should not diminish much when the differential is run with the wheels off of the ground. Wheel bearings produce a rough growl or grating noise when in need of repair or replacement. This sound will continue when the vehicle is coasting and the transaxle is in Neutral. Since these bearings are not preloaded, the noise should diminish considerably when the wheels are off of the ground.