I use apostrophes for plurals of numbers, e.g., four 7586’s, but learned not to do so for abbreviations, e.g., four FETs. My boss at the time enjoyed catching my errors in reports, e.g., writing “ordinance” for “ordnance”.
I use your style for numbers too. So I guess my informal rule is that I use apostrophes to prevent misunderstanding where the trailing "S" might be interpreted as part of the thing being discussed. In part numbers, a trailing "S" can definitely be a significant character... so your example is perfect. But I'm sticking with my method for acronyms too, for exactly the same reason.
Ordinance vs. ordnance is a great one.
You'll love this: I write my own patents before submitting them to the attorneys for "legalese". Far cheaper and more accurate to have ME write about the topic than to partially educate an attorney (at our expense) and then pay them to write what I would have written anyway (at our expense) so I can then review it (at our expense). On a network interface patent there was a certain important characteristic about how data was managed through the interface, and I used the word "transit" to describe the conveyance of data from one side of the interface to the other (example: "The byte then transits the interface without having to be written into, and later read from, the shared memory").
I submitted this for legal review, and it came back with a fat invoice for "corrections". That was wildly out of character as I'm a very careful writer. Upon inspection, I found that every single instance of the word "transit" had been replaced by some paralegal with the word "transmit" and we had been billed accordingly. Nobody asked, nobody emailed, nobody read in context - they just "knew" it was related to networking so I must have meant to use the word "transmit", right? Yep, I must have somehow mistyped every single use of the word "transmit" in the entire document. Yeah, that's logical.
The above sentence would thus become the nonsensical "The byte then transmits the interface without having to be written into, and later read from, the shared memory". Pretty cool being able to transmit hardware, eh? Apparently this is part of the overall intellectual property package surrounding my perfecting of the Star Trek transporter.
Bad enough to be miscorrected, but then to be BILLED for the service. BTW, they initially argued with me (the author!) but when I cited a couple of their "corrected" examples they conceded defeat, undid their "corrections", and the invoice disappeared.