Thanks, guys. I did both. Got my spouse to enroll in a free-two month KU subscription and download the ten books that are in KU. Then I tried the "Edit Content" trick on the others and got exactly the information I needed about which file version was on Amazon.
What I will do with it is a different story. I do not format my own books, and in the past I've had my formatter update them. As I got busy and the formatter did, too, not all of them got updated before that formatter turned me loose. Starting over with a new formatter who says any changes in a book he did not format would require a complete reformat, I don't know if I'm walking into the a spiderweb for the future. Plus the idea of paying all over again for formatting is daunting. I don't know enough about formatting to understand why a file would have to be reformatted from scratch. I've been considering sending one of my books as a revised Word doc to D2D instead for their free formatting, although I'm not sure how much prep work I would have to do in advance, such as not indenting the first paragraph in a chapter, and the like.
I'm not sure of the value of all the updates I've done in the past, either. At first it was just dealing with a few typos. Then it was updating my Books By pages with links in the frontmatter and backmatter to encourage instant purchases. Then I changed covers and needed to remove the old cover design credit from my copyright pages and have the old embedded cover removed. Then I added some first chapter excerpts at the ends of some of the books. Then I finally got it together to produce a free novella as a newsletter signup incentive, and I had that, with the cover of the novella, added to the frontmatter, and I also updated my link to Mailerlite from MailChimp in both front and back. A lot of fiddling, but my old formatter would do it for peanuts.
That's a lot of activity. I felt my edits to text were important, but I don't have evidence that all these pleas to sign up and to write a review and to buy the other books I have out have produced much of anything.