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

300 5cyl. homemade prechamber puller

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.