I was changing the oil filter on my 83 300d and leaned on the check valve and broke an inlet off.
Then noticed the other inlet was broken off too!
Can anyone help me find this part or the part number?
Looking for 140 on the diagram.

I can't vouch for the W123, but the entire line from the vacuum pump to the brake booster must be replaced on the W126. The check valve is part of the brake booster line and they do not sell the valve independently of the line.

We've all broken that valve at one time or another. A replacement line is about $50. or so.........

I agree, you need to replace the entire line (I've broken a couple). This is what you need:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41Y90M7ZZA&year=1983&make=MB&model=300-DT-001&category=All&part=Booster+Vacuum+Hose&appChassis=_any

A good source for part numbers, etc. is the Classic Center in California. With your VIN number they will be able to give an accurate part number, retail cost and part availability. The Classic Center does not sell parts itself.

Jim W.