I doubt that the either the axles or the struts would creak or groan. The sway bar bushings could make noise. I assume you have a 4matic, since the standard suspension doesn't have struts. You should have lower ball joints on the front that can make noise, as can rubber bushings which are common on the front and rear suspension. I don't feel his diagnosis is really related to the noises you mentioned. You may need all those things, but I would get a second opinion.

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'97 E 300 D