I have just been poking around in the trunk of my 280E to see how extensive a patch of rust around the LHD tail-light is.
I pulled out the black plastic lining and found a slim aluminum tube that appears to have no purpose.
The tube is about 20 inches long, is slightly bent, and is connected to a black box sitting just forward of my (non-standard) antenna assembly. The tube is crimped at the unattached end, and appears to be filled with grease. It runs horizontal and parallel to the rear fender.
Does anyone know what this tube is? Is it something to do with drainage or the central locking? I've checked my M-B engine/chassis parts book and Haynes manual, and can find no reference to it in either.