Try your local dealer. The part # is HWA2014000125, at least that's what I have written down. You can also do a search in the W126 forum, discussed many times there and someone may still have some for sale.
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!