Diesel911 mentioned several choices... and you just said... "thats the one" ... so, still not helpful in determining what you need to know.
basically, nearly everything under the hood of a 82 300D is going to be vacuum... no pressure.
the "green things" in the vacuum lines, are restrictions to limit vacuum flow for certain vacuum consumers...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!