Here's one example of such a tool. This is a kit. I am sure that you can buy just the piece for your system for a lot less.

http://www.autobarn.net/xxxw-mas58490.html

I know nothing about this particular seller. This is just one that I found with a quick Google search.

huhh . . . what? (wakes up from long sleep) Someone resurrected this thread?

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1986 300SDL, 362K
1984 300D, 138K