A very thorough analysis of the Oberdorfer 202 cooling pumps.
The only question I have is regarding the grease cap fitting. I don't see that part in the exploded diagram you attached. Does this newer 'N' model pump not have the grease cap like the older models?
I ask because I recently replaced our nearly 10 year old Oberdorfer M202 pump with a new pump sold by Moyer Marine that uses bearings for the shaft instead of the grease cap fitting. The pump I used is the MMI 502 pump shown on this page Moyer Marine Atomic 4 Engine Rebuilding and Parts
I found a lightly used one for $50.
The grease cap is used instead of the carbon bushing on the N202M, the N202M-03, and N202M-07. All of these pumps use a 2 bolt flange. The -03, and -07 pumps are used on the Atomic 4, and the -07 is used on the M15 diesel. The -03 is a lower capacity pump (3½GPM vs 6½GPM @ 1700 RPM).
The N202M-15, and N202-16 have a 5 bolt flange (but you only use 4 bolts) and use the carbon bushing instead of the grease cap. The -15 is used on the Universal M-12, M-18, M-25, M-25XP, M-30 and M-50 engines. The -16 is used on Kubota branded engines.