The upper ball joint comes complete with the upper arm.
You will need a two jaw puller to separate the ball joint from the spindle. You will need to remove the bolt holding the arm to the chassis. The passenger side is failry easy in that you must remove the bettery. The drivers side is a PITA becasue the master cylinder and various pipes are in the way and the bolt must be removed from the rear. When I replaced that side, I put the bolt in from the front. I used some long jawed needle mosed type pliars with rounded ends to grab the bolt.
Be aware, you may find the lower ball joints are also bad and the chassis mounted brake rod ball joint is bad as well. Examine the boots for cracks or holes.
The lower ball joints require a special tool. Take the spindle to a MB shop. I did.
http://www.peachparts.com/shopforum/showthread.php?threadid=91934