http://catalog.peachparts.com/ShopByVehicle.epc?q=1982-Mercedes--Benz-300d-Suspension&yearid=1982%40%401982&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6190%3AED%7C10000135%3AMBC%7C1504%40%40300D&catid=241464%40%40Suspension&subcatid=241520@@Guide+Rod+Repair+Kit&mode=PD

Guide Rod Repair Kit. $14 at Fastlane (Buy Parts link)

Yes. That part missing will cause clunking. Before doing any work on the lower control arm that involves the spring, do a little research. A standard spring compressor doesn't fit well and creates a very dangerous situation. I can't tell exactly from the pic if you'll need to move the spring.