I would second the above info. I don't know about your W126 chassis, but on the W124s like mine, front swaybar bushings generally last about 75 k miles. Mine made a "thunk" sound over bumps, esp. with the wheel turned slightly.
Cheap and easy fix.
My dealer misdiagnosed the noise as blown shock tower mounts and estimated $1200 to fix. Instead I learned about the swaybar bushing problem and spend $50. Problem solved.