I think the best place to buy your covers is GAHH. If you were to go to Mercedes and ask for a set they wought send you there.
If you need seat pads I have a set up for sale. They are used but are in great shape. I also have a set of used cover as well in great shape no ripes or tears. These cover and pads are out of a 1982 380 sl that had 88,000 on here
Thanks Pete
Newmanpc@comcast.net
WWW.Gahh.com