Just happened to me a few weeks ago. Looked like it was leaking from the rear deck area. I checked to make sure it was not the seal for the trunk lid - it was good. Only thing left is the rear window seal. reading several posts here it seems to be a common problem with old mercedes - rubber ages and shrinks allowing water to get by. Mine looked ok, not cracked and dry looking, but you apparently can't go by looks. Ordered the rear window seal from Adsit (sorry Phil, they were cheaper). I called a couple of body shops that do restorations and/or work on older cars to get a recommendation for a glass outfit that could handle the old style seal with chrome trim like we have. They both said the same guy, called him and he installed my seal - rained for a couple days last week and no leaks
