Had the same problem w/ my '94 S500.
Front pads would make a 'grinding' sound; the rear pads would squeak (very, very loud!) when backing up. Both were on the car when I bought it.
Replaced both with Textron pads for front and rear. No grind, no squeak. As I understand it, Textron are MB pads without the MB star on the box (ie Textron makes them for MB).
Regards . . . . JimF
'94 S500 Cpe
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