This car was prone to the steering gear box loosening on the frame. Verify the 3 bolts holding the box to the frame are not loose. Left loose, the frame will crack! Do the front shock rubber bushings look in good shape? They can peel away over the years allowing the upper shock mounting to be loose causing a clunk. Look at the flex joint connecting the steering column to the steering gear box. It can deteriorate as well, causing a clunk as the wheel is turned.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.