If you are replacing the lower ball joints you are already into it far enought that replacing the upper ball joints will be a part of the project. The upper control arm and ball joint is all one unit and in most cases comes with the bushings needed for the sway bar and arm. When I did mine I jacked up the car and then lowered it down so the lower arm rested on a jack stand then I could remove the entire steering knuckle with out having to use a spring compressor but if you are going to do this make sure the lower arm bushings don't need to be replaced.

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1983 300SD
200000miles