Well that was dumb! My first post, and I post it to the wrong forum (my vehicle-of-interest is a '68)!! If a site host happens to see this and is willing to transfer this thread to its proper place, that would be a kindness. Meanwhile . . . .

I'm an old guy, but I don't know the term, "warranty plate". There was a Grumman-Olson badge on the dash, but it has been scraped and bashed enough over the years that any numbers are unreadable, and anyway that's just the body; it's a Ford truck. What I do have, and maybe this is what you're after, is the VIN number:
B26636DG40JLC57392
It was last licensed commercial, 10,000 gross wt..

I found the brake switch, a funny-looking metal affair, originally Borg-Warner as I understand all Ford brake switches were, and available now as a Niehoff S643 for $10.49 at O'Leary. That should get the truck to where I can drive it home, about an hour's drive.

Thanks for the interest and ideas.