That's a $.25 piece! If the radiator tank's not broken, you can simply replace the little elbow-I broke one, and have since replaced it on both of my gas-powered W124s.
Just be careful removing the broken-off piece-you want to avoid dropping it down into the radiator if possible.
I STRONGLY recommend that anyone who has a W124 and hasn't replaced this little mother, than do so at your earliest convenience!
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car