You can't just replace the ball joint on these...you need to replace the entire control arm assembly. Its not a tough job at all, but does require some finess(i.e. hammer) when removing the ball joints from the spindle. Here are some instructions you can print out. Also....buy your control arms here....they hook us up a lot.
www.rockauto.com
Front....
REMOVAL
Turn off air suspension switch located in LH side of luggage compartment.
Raise vehicle on hoist.
Remove wheel and tire assembly.
Disconnect air suspension height sensor from front air suspension sensor pin.
Remove and discard nut from front suspension lower arm strut. Pull off dished washer. CAUTION: Do not allow steering knuckle/halfshaft to move outward. Over-extension of the tripod CV joint could result in separation of internal parts, causing failure of the joint. NOTE: Make sure steering column is in unlocked position. DO NOT use a hammer to separate ball joint from front suspension lower arm.
Remove and discard lower control arm ball joint nut. Using Tie Rod End Remover TOOL-3290-D or equivalent, separate from front suspension lower arm. Use extreme care not to damage ball joint seal.
Remove and discard front suspension lower arm inner pivot bolt and nut.
Remove front suspension lower arm from front suspension lower arm strut.
INSTALLATION
NOTE: Make sure the front washer is present at front suspension lower arm strut-to-arm attachment.
Insert front suspension lower arm strut into front suspension lower arm rear strut bushing.
Position front suspension lower arm into sub-frame bracket. Install a new nut and bolt. Tighten to 98-132 Nm (73-98 ft. lbs.).
Assemble front suspension lower arm to ball joint stud of the front wheel knuckle. Use extreme care not to damage ball joint boot seal.
Install a new front suspension lower arm-to-ball joint nut. Tighten to 68-92 Nm (50-67 ft. lbs.).
Clean front suspension lower arm strut threads to remove dirt and contamination.
install dished washer, dished side away from front suspension lower arm rear strut bushing, and new nut on front suspension lower arm strut. Tighten to 98-132 Nm (73-98 ft. lbs.).
Attach air suspension height sensor to front air suspension sensor pin.
Install wheel and tire assembly. Tighten lug nuts to 115-142 Nm (85-105 ft. lbs.).
Lower vehicle.
Turn air suspension service switch ON.
Front lower.....
REMOVAL
Turn off air suspension service switch.
Raise vehicle on hoist.
Remove wheel and tire assembly.
Remove air spring.
Remove brake anti-lock sensor wiring and rear parking brake cable and conduit and routing clips from front lower suspension arm.
Remove front lower suspension arm-to-rear wheel spindle nut, washer and bolt.
Remove front lower suspension arm-to-body nut and bolt and front lower suspension arm.
Remove rear suspension arm adjusting cam kit from front lower suspension arm if damaged.
INSTALLATION
Install rear suspension arm adjusting cam kit if removed.
Position front lower suspension arm into vehicle. Install front lower suspension arm-to-body bolt and nut. Hand tighten nut.
Install front lower suspension arm-to-rear wheel spindle bolt, washer and nut. Tighten front lower suspension arm-to-spindle nut to 68-92 Nm (50-68 ft. lbs.). Tighten front lower suspension arm-to-body nut to 68-92 Nm (50-68 ft. lbs.).
Position rear parking brake cable and conduit and rear brake anti-lock sensor wiring routing clips as necessary.
Install air rear spring.
Install wheel and tire assembly. Tighten lug nuts to 115-142 Nm (85-104 ft. lbs.).
Lower vehicle.
Turn air suspension service switch ON.
Check and set camber and toe if necessary.