I respect your knowledge from collecting such a long time. You are right that I'm pretty new at this game, so I don't want to come across in the wrong way. I was basing this off observations I've made and what other long term collectors have told me.
I like Nagoya aot too because you are very right about them using old parts throughout their later series. Best example I can think of is the 8th where randomly the protected front sight and receiver with the "Type 99" text comes back from a brief period after several thousand rifles made without them, only to return back to standard Nagoya last ditch pattern later on. I know those type "A" receiver also appears at random in the 11th.
Anyway, I've just never seen a 5th series in person or posted somewhere with (or without) a monopod that really showed the look of one being on the rifle since the war. I've seen some added later, usually proofed wrong or not showing the old wear in that area most rifles with a pod had. However, I'll admit that the lack of something from a pretty tiny pool (what I've seen in 4 years) doesn't prove my point. I want to keep an open mind this this field since nothing is set in stone, as I've come to find out.
Best regards, and respect.