I wanted to follow up that when I took my Crossfire in to my independent Mercedes shop, the only thing he could find was that my left rear shock was wet with fluid so he suggested replacing the rear pair. I ended up replacing all four corners with KYB and not only did the creak go away, my car was transformed! All the wallowing and crashing (which I didn't think was that bad) disappeared and the handling tightened up. Made me realize I could have done that a few years ago. Sweet.