BWSE,
Just to add to your research....
the made in Czechoslovakia had several versions.
The earlier slugs the "MADE IN CZECHOSLOVAKIA" was actually under the text of "OFFICIAL"
The pucks from the 50s thru 70s also had a small v after Czechoslovakia
The mid 70s, the word "OFFICIAL" was moved to the opposite side of the puck (as in the pictures)
I know that UND had pucks by InGlasCo starting in the late 80s/early 90s. (InGlasCo put out pucks starting in '84)
There are also a few General Tire pucks floating around (those were around 85-90 then later taken over by Lindsay and as of this year ProFlex)
That's how I placed this puck late 70s to mid 80s
I have Brown, Cornell, Western Mich, and Northern Arizona on the same puck cut for comparisons.