The prechambers for a 61x.91 normally aspirated engine are NOT the same as those for a 617.95 turbo engine (illustrated in job 01-417) and they must NOT be interchanged (OM60x turbo and non-turbo prechambers are likewise different and can't be interchanged). Last time I checked, Balo made prechambers that were considerably less expensive than the factory parts and I've had NO trouble with the Balo replacements. I haven't bought any for 4-5 years but prechambers for a 601.921 engine were ~$60 each then vs $90+ from Mercedes.

Marshall