Hi all, I have a 2003 Chrysler Crossfire which had creaking rear suspension. A common problem is the Control arm bushing, also called the "Knuckle Joint Bush" or "Rose Joint" - Chrysler part number 05114234AA. I had both replaced and voila, problem gone. My mechanic works on Mercs and this is a common fault on the SLK. Hope this helps someone else as it is an annoying problem !!