Upper Ball Joint: Description
WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
The ball joint is pressed into the upper control arm and has a tapered stud for attachment to the steering knuckle. The ball joint stud is attached and locked into the steering knuckle using a special nut. The ball joint is a sealed-for-life type and requires no maintenance. If the ball joint is defective it will require replacement of the entire upper control arm.