Dan,
You can probably just get some numbered tabs at Staples or Office Depot, or maybe an old school electrical shop.
TV shops used to sell sheets of them to use to keep track of the tubes in your TV or Radio, when you had to pull the tubes to take to the shop & test them all on their tesing machine to know which were bad, in order to get them working again. I dn't think they have those anymore.
You could also just hand letter some small Avery labels from Staples/O.D. too, or cut up larger sticky-back labels to make the tabs.
Don't forget to put tabs with the same number on the other receptacle or connector end too - 2x all numbers for both ends.
I don't think those were anything original, but rather something some PO or their mechanic/shop used to keep track of them while working.
Good Luck!
Tom
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