License plates

Someone from Tennessee or someone with the knowledge, I need some assistance. Plates on trailers. I have always seen the plates on any trailer registered in Tennessee start with a U. Has anyone ever seen a plate start with a Z? By looking at the plate, you can instantly tell the state didn't run out of number combos and move to Z, this plate looks old, real old. The trailer itself was manufactured late 90's early 00's.
Only thing I could find was a site referencing commercial busses.

 

Well, the plate in question is on a bulk trailer. All of our other trailers have TN plates as well, but they all start with U. This is the only one I've seen starts with Z. VIN on registration matches plate on trailer but license plate doesn't. Spoke with maintenance supervisor and she couldn't find this number in our database. For the time being, I am instructed to put it OOS, and remove the tag. She is going to report the original stolen to the TN dmv. This wasn't recent either.

 

Here's my issue. I originally caught this trailer on the yard in June or July of 23, same issue. The guy in maintenance I told about it made it sound like it was going to be a chore to research it. Now I spotted it on our yard in Oklahoma. I don't know where it went to after that, but flash forward to now when I grabbed it in Nebraska. It had been loaded in Georgia dropped in texarkana where a shop did an inspection (I feel they should have caught it) then taken from there to Nebraska where I got it. We have around 110 drivers and I would guess maybe 30 check paperwork on trailers. For the most part, they grab and go. These same people would then play the dummy card if dot asked about it. I know it happens at a lot of companies, but it is frustrating.