You need this hose:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1XL0VHEI020Y19F8N8&year=1983&make=MB&model=240-D-002&category=E&part=Fitted+Fuel+Hose

Check with Roy. The two hoses are probably identical and you'll need a pair.