I need to replace my antenna mast (motor works fine). It looks like there are two available for my car-- she's a 1980 300TD-- one is "smooth", the other "toothed" Another post linked to a great 2 for $14 deal on eBay which is right in my price range. It looks like these are only the smooth ones though, so my question is... Will this work for my car? And what's the difference between smooth and toothed anyway? I haven't yet taken the thing apart to know if it's self explanitory or not.

Thanks in advance,
Christine