Follow up thought. Mounts, specifically the front motor mount which is located near the passenger side front wheel on the 5 cylinder engines. That one does wear out at high mileage. Had to replace it on my 850 at 200k+ miles. It is strange, however, that the clunking would show up out of the blue without any other symptoms.

Also check the upper torque mount. If it is shot perhaps it is allowing the engine to shift when you go full lock with the steering?
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Will I buy another Volvo??? We'll see....