I don't know about that particular model, 2gofish, but here's a page of color swatches for 1991 Mercedes: http://www.tcpglobal.com/aclchip.aspx?image=1991-mercedesbenz-pg01.jpg. Hope that helps!
Go on ebay and search for 1991 sales brochure and/or 1991 mercedes color chart. Usually $10-$15 .....
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