You'll need two of those copper seal rings, M-B dealer part# N.007603.012110 or if you buy your parts online search for part# A8092-12361.

If you have a large auto parts store in your area that sells Dorman Fasteners, search for copper washers with these dimensions: 12 X 17 X 1.5 mm (I.D. x O.D. x thickness)

__________________
1989 300SE: 200,000+ and going strong