I did the experiment on my 300SD parts car, so no I have not yet put the spring in. I am planning to rebuid both lower control arms and bearing mounts from the parts car and then install them on my daily 300SD. I don't think I will need to use any compressor to put it back. It looks like I will swing the control arm up untill the spring case makes contact with the bottom coil then start pumping up the floor jack.

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it