Did my shocks and steering damper, now what is this?
 

I replaced my shocks with KYB's this morning. Once I had everything I needed it was pretty smooth, but I did have to saw off the top screw on the passenger side shock. Once I replaced the shocks, I noticed the top of the replacement shocks have a much longer mounting screw, by like an inch, so I double bushed them. Why the extreme difference in length? Is there supposed to be a bushing underneath the mount? I didn't notice that on the original ones and it seems like it would change ride height, even if just an inch or so. I may go back and do that and see how it is later. As I think about it it makes more sense to me.

Anyway, I did the steering damper and took a test drive. The steering has a much more accurate feel and is very direct, and the car feels great, but the problem I wanted to cure with new shocks is still there. When there is a hard bump on the passenger side, there is an "echo" to the bump, it sort of reverbs a bit, and it feels really loose under there. Its only on hard bumps, but it reminds me of when I needed ball joints on another car. I imagine thats what it is. Thoughts?

Here is a shot of the top drivers side shock on the CD, these have not been replaced. They're Bilstiens too. The extra length on the threaded rod shouldn't be an issue, (I would think those [KYB's] are generic) just tighten it down as per MB specs, the rubber bushing is to squeeze out a bit, as I recall.
EDIT: pic added.

Have you checked your brake support joints? The brake support goes from the bottom of the lower control arm rearward to the frame floor. It's basically a sealed ball joint that threads to the support rod which is bolted to the lower control arm. If the boot of the ball joint tears, the integrity is lost and the joint can fail. As you have described, it makes the most noise on bumps. 33-540 to inspect it (though you'll probably only do a visual), and 33-515 to R&R.

How are your upper control arm bushings? If they're in bad shape the UCA can move around in the tower.