Sorry to hear that you are having problems with NC. Been there and done that. I had to take a 66 Mustang to another state and get it titled to avoid the stupidity in NC. Hopefully you wont need to go that far. Is your VIN plate attached to the drivers door frame or the glovebox? Most of the frame stampings I have seen are located on the front (first) crossmember in front of the engine, passenger side or along the passenger side of the frame rail towards the front. Sadly, most of those stampings are often faint from corrosion or poor stamping at the plant. I have had a couple of trucks where paint filled in the stampings. As far as I know (and I could be wrong) there were no stampings anyone else on the frame, so pulling the cab won't help. I would try to use some paint stripper and not an abrasive sandpaper on the frame to see if you can reveal a number on the frame. Sanding could only remove the number. Good luck!