Im looking for the same thing for my 82 sedan. Im planning to buy the parts below. Give Phil or Roy a call...

Front insert part...(same part # as my sedan)
http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1Y30QN7KB2590HRHXY&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=P7040-11849&application=000026212

For the rear...(for the wagoneers)
http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1Y30QN7KB2590HRHXY&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=P7040-11849&application=000026212

Unlike my Toyota, you just replace the rubber insert itself instead of the whole wiper.

Hope this helps,
dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car