I also have Monark Nozzles bought from forum member C Sean Watts in 2 of my vehicles (made in Germany). (He can also rebuild your Injector for you; I did my own.)
Mercedes Sourc* sells them also.

Me thinks kerdatdi may still sell bosios and for less than some other places (made in Italy).

Somewhere there is a long thread or 2 on the same subject.

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84 300D, 82 Volvo 244Gl Diesel