I have a set of chrome wheel arch trim pieces that I just removed and cleaned up from my 1986 300SDL. They are for sale.
The parts are thin chrome strips that are well used (car has 250K miles), so they are not perfect, but the part that shows is fairly good. They came with a rubber edge strip which is missing from the 2 rear pieces but is present for the front 2. These 2 rubber strips are in fair/good condition. The back of the chrome strips still has the original Mercedes part stickers.
I know they fit a 1986 and 1987 W126; very likely to fit any W126. Don't know about coupes.
I'm asking $30, but make an offer if that is just too much.