The stampings you see on the topside of the fenders (inside edge with hood open) and the Ford oval - those are the date stampings of the sheet metal. Those are genuine original Ford parts put on the vehicle as it went down the line.
The one pic where you see an additional flat piece of steel and numbers on it under the fender - depending on where it’s located (hard to tell in your image), but if it’s forward towards the front nose cone, that is the winglet that is welded to the inner fender structure and contains the last few digits of the actual VIN. There should be one on each side at the front of the car and are visible if you remove the fenders. If you remove the black plastic inner front wheel liners you can see those winglets, but won’t be able to really read the VIN if the fenders are still on.
This is a thread I posted over on Corral a few years back that contains A LOT of the info for where all the VIN’s should be and coding etc. It’s too lengthy to repost here, but there’s additional info posted by others too which is helpful for any Fox Mustang research.
https://www.corral.net/threads/ultim...#post-18639446