Today, my son and I gassed it up, fixed my fill tube, and drove up to Tehachapi to return a few things, that I no longer needed. Unfortunately, I'll have to go up there AGAIN, later this week, Radio Shack was closed. Next time I'm at ACE, I'll get the specs for the bolt/nut. When I picked them up, I almost bought "chrome" ones, but then caught a glimpse of these a couple sections over.
My son ran the nut down, in this case up, the bolt from under the bed. We then switched places, so I could make sure that the nut was on there good and tight. Survived our 80+ mile trip to Tehachapi, from Edwards AFB, and back to the house.
A few weeks ago, I was filling up and noticed that another Silverado owner, from Florida, had the same issue. He was reinstalling his broken plastic fastener, when he was done filling up, just like I was repeatedly doing, until today.