The car has been vibrating more as time goes on so I'm replacing the flex discs. When I took the rear disc out I found another part sandwiched between the drive shaft and the flex dics. It's an original Mercedes part "A1404110347" and while the flex joint looks a little cracked, this part is very much past prime and is most likely the source of most of my vibration. I can't find this part anywhere including the dealer, and it's not part of the "rear flex disc kit" from any supplier I can find. Plus no one I've talked with has ever seen or heard of it. Can anyone tell me what the deal is? Can I just leave it out? The part is pictured below.
