If I'm not mistaken, 1983 may have been a transition year for the smooth/toothed drive in the antennas. I also just replaced a mast in my 1983 300SD and it had the toothed drive belt. When I was looking at various online catalogs for the mast I saw enough conflicting information to make me a little nervous about placing my order without knowing for sure. You probably should pull the mast out and check before you order a replacement. It only takes a few minutes to do and you would be certain you are ordering the correct part.