Benzboy87:

Is this the part you're referring to?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog2.mercedesshop.com/&cookieid=1E50U2ODS1E50U2US7&year=1991&make=MB&model=300-SEL-006&category=R&part=Climate+Control+Unit

Thanks.