Please Help Identify This Part

[Zoonhollis]

1995 E300 Diesel (606)

This is a cooling system component that my local MB dealership cannot seem to identify (big surprise). It's near the firewall on the drivers side and it has recently sprung a leak. On the "T" section of the hose connector reads this:

MEO 20.127 2.3

...and here's a pic. Any help appreciated.