Are there not several items that could contribute to this? Some being minor and others obviously being major. This appears to be only affecting the pass side rear.
respone on 2004 Mercedes-Benz E320
Here's a diagram of the rear shock area http://www.parts.com/oemcatalog/index.cfm?action=getJointLocator&siteid=2&Sectionids=24,0&groupid=20135&subgroupid=61669&componentid=&makeid=67&model=E%20Class&year=2004&graphicID=F348080&callout=1&catalogid=1&displayCatalogid=0 Quite complicated to diagnose over the internet, Hope this helps.