Here are 3 firms I've "bookmarked". All deal in used Benz parts. I've only listed the middle of the address (no www.etc)
tristarparts.com
mercedesdismantlers.com
findpart.org

I just remembered Adsit(?) They deal in new and used. There are also
pick-a-part yards but I doubt if they have anything that old.
Good luck,
Anziani
'97 CL600 50K