I have a 1983 240D. The rocker panels have rusted after 19 years. I order new ones at the MBZ dealer. The body man at MBZ said to buy the entire rocker panels ($146) because the skins are to hard to line up with the jack mounts. So now that I have them how do I install them? I took it to the local body shop Non-mbz to get an estimate and they look confused on what needs to be done to remove the old and replace the new.