In Reply to: 9N and 8N camshafts posted by Steve Dabrowski on October 26, 2017 at 19:21:59:
John Smith says, "The last production press-on camshaft gears were in '42. After that all tractors, including all 8Ns, had the bolt on timing gear. The camshaft listed on this site(YT)as "for press on gear" is referring to the small distributor drive gear that presses on the end of the camshaft, NOT the timing gear which bolts on."
I have seen camshafts both with & without the fuel pump lobe.........maybe this could be a difference you are looking for?