Diesel Injector Plug.
This is used on the rear injector to cap/blank off the fuel return barb.

These numbers have been superseded:
MB# 0009871145
MB# 4030700355
MB# 6010700355

Current production.

Note: This is the unit I use.
Diesel Injector Plug, fuel return. Rubber/Metal
MB# 4030700055
http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?SUPERCAT_FLAG=Y&make=&please_wait=N&forumid=&threadid=&command=DWsearch&description=4 030700055&I1.x=3&I1.y=7


EPC shows a newer cap/plug that is SPECIAL ORDER item.

Rubber cap
MB# 6040700255
http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?SUPERCAT_FLAG=Y&make=&please_wait=N&forumid=&threadid=&command=DWsearch&description=6 040700255&I1.x=9&I1.y=6



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__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

Looks like I'll start nabbing them from any diesels I find in the JY