Prechamber and threaded ring threads

[KCM]

I am considering buying or making a prechamber puller and prechamber threaded ring removal tool for OM621 and OM617 engines. From previous posts on this site

http://www.peachparts.com/shopforum/showthread.php?t=58446&highlight=prechamber+tool

it has been stated that the prechamber threads are M22x1, which are the same as some Nissan half shafts and also some bicycle crank pullers/pushers.

Does anyone know what size and pitch the threads are inside the threaded ring, where the injector screws into? Does anyone have a cheap source for factory made tools? The cheapest I found is $40 to $50 for the puller and $80 to $90 for the ring tool. And, can anyone confirm that the OM621 engines from the 1960's use the same tools as the OM616 and OM617 from the 1970's and 1980's? Thanks.