Howdy all, and thanks to the member who e-mailed me about this mystery.
The last 4 digits are an expression of Goodson-Todman's long-used numbering system that is common to their shows and is really quite simple. In the example posted from November of 1970, "1025" indicates that this is the Friday show ("5") for week #102 for this version of WML. This is borne out by the fact that the show from the summer of 1968, when the show was yet to debut, logically is the Wednesday show from week #7. This numbering system is still used to this day on TPiR.
Tapes of syndicated shows were bicycled from station to station in those days. It took months for an episode to make the rounds to all the stations that individual copy was earmarked to be sent to. As such airdates, the usual way to identify an episode, could not be used.
The fact that the prefix "0076" is common to both episodes taped two years apart suggests that it is simply a production number - a number assigned to all episodes of this incarnation of WML. The "0076" is not used in the logging of the shows' panelists and contestants in GT's surviving paperwork from the show. I suggest it was used for simplicity When a station referred to a specific tape it need only use the 8 digits; no show name was necessary. So when a call came in that episode #xxxx-xxxx was damagaed beyond the ability to be aired or the show had some content being referenced, no show name was needed. It was simpler for a company that had dozens of tapes being mailed all around the world (WML, TTTT, IGAS, etc.)
My time on the set as a contestant and as a guest of Johnny O was around the summer of 1971. I can provide these reference points if it helps anyone:
Week #137 taped on 8/12/71
Week #139 taped on 8/26/71
Week #140 taped on 9/2/71
Week #141 taped on 9/9/71
Week #142 taped on 9/16/71
Thanks for the shout out!