Well, I had to try the local dealer who in turn said there were NO rear 560 sel sway bushings at any Benz dealer in the U.S. any longer. The good thing is, they will get them from Germany for $10 a piece regardless shipped to my house in a week.
Parts.com seems to no longer have any in stock as well and at least from the person I spoke to, they no longer plan to carry them as they are obsolete (?!)
Let's hope this solves my creak and clunk on my rear passenger side or it's on to inspecting bigger components!