I have a 2005 Magnum RT. The other day, I had an issue that turned out to be a small plastic sleeve that mounts around the drive shaft up by the transmission. It was worn and started rattling and ultimately came off. I believe it is some sort of covering to protect bearings but not mechanical and the mechanic was useless. I need to replace the part but don't know what it is called or the extent of the work. Any suggestions?