I used some Mercedes orange sealant MB No. 002 989 00 20 10 on the front covers of my 400E and it was $55 ten years ago. It was really good stuff. I wouldn't mind having another tube of that if I could get it for a reasonable price.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles