You will need to lower your car onto jackstands, under the rear jack points, then, remove the jack from under your rear axle.

Then, position your jack on one side of your axle and gently jack up one side of your axle. This will allow the spring on the other side to be removed. Install the new spring, and then do the same on the other side.

Good luck!

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If it needs to be maintained, repaired or replaced on a 1990 240, I've probably done it. '90 240DL, 313,800 miles, will she make it to 400K ?? >>You haven't really worked on a car until you draw blood<< :-}