U-Joint Bearings
WARNING: This page is about a different car, the 2002 Mercury Mountaineer, 2002 Ford Ranger, 2002 Ford Explorer Sport Trac, 2002 Ford Explorer Sport, and 2002 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
Place the vehicle on a frame hoist and rotate the drive shaft by hand. Check for rough operation or seized "U" joints. Install a NEW "U" joint if it shows signs of seizure, excessive wear or incorrect seating.