The '81-'83 had a single row timing chain. Unless it has been converted to double row then pass. The '84-'85 had the double row but there is no guarantee on that either.

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Here's one http://www.benzworld.org/forums/r-c107-sl-slc-class/1471540-first-post-sadly-i-need-help.html

Here is some history
http://northernresource.com/mercedes/107-horsepower.htm