you may need a shop press for this
this should help..please print
Lincoln Aviator, Ford Explorer, Exp Sport, Exp Sport-Trac, Mercury Mountaineer 2000-2005
WARNING Do not loosen the axle wheel hub retainer until the wheel and tire are removed from the vehicle. Wheel bearing damage will occur if the wheel bearing is unloaded with the weight of the vehicle applied. NOTE Have an assistant press the brake pedal to keep the axle from turning.
FIG : Pressing out the bearing
well,if you have mechanical experience and to tools..this should be no problem..it would be a good idea to let a shop replace the bearing..you may save a few bucks....just take your time,follow the directions,,,you can do this