It looks like you have a few little issues, first you need to replace the old 3-way and 4-way vacuum connectors:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41VN00Y6VJ&year=1984&make=MB&model=300-DT-001&category=All&part=Vacuum+Hose+Connector

You also need to replace the injector return lines that are weeping:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1CQ0J3JZ41VN00Y6VJ&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=E5000-103594&application=000016757

The part with the disconnected line appears to be the over-pressure valve that should be in the line between the intake manifold (banjo bolt) and the injection pump. Has yours been bypassed?