Mine had a similar problem. It turn out to be the rubbers on the end of the sway bar. Crawl under and see if there is a slight gap between the rubber and steel. I did a foolish thing and squirted some lube on the rubber. Then I had the rattle all the time. Fixed now with acouple of $2 parts for fastr lane

__________________
Ricali

03 C240 4matic wagon
95 300E 234,000
7 prior 240;s 5 still going
81 300sd gone
65 230sl gone
49 Studebaker Champion
90BMW convert.167,000
60 Dodge D-100