Diagnosing a "clunk" in the right rear

[Verhag]

Curious.....I have less than 1000 miles on 2000 S....experiencing the same "clunking" from what seems to be right rear. To me it gets more pronounced the more the car warms up...when I pull out of garage it feels like new, tight,solid like one comes to expect in a German car....then affter afew miles, any little bit of rough road results in this "clunking" noise from rear end. Top down or up, the same. Sway bar is tight. Should I start with rear track arms (look like tuning forks) or front motor mount?

Willing to do it all, but I prefer to start one component at a time....suggestions?