I was discussing this topic with a friend who used to be a senior police officer and who is a classic car 'nut'. We were talking about how badly the screen scuttle panel rusts on the late cars in particular, these being the cars with the VIN number stamped into the scuttle front edge.
Now the screen scuttle is available as a complete replacement and this is often necessary, so the car ends up with no VIN stamped in. There are, therefore, 3 options:
1. The leave it without a stamped in VIN number.
2. To cut the piece off the old panel with the VIN number stamped on it and MIG weld it into the new panel.
3. To buy some metal stamps of the right size and stamp the number into the new panel yourself.
We thought about this and decided that having no VIN number could be a problem when selling the car, but welding in the old bit of scuttle or stamping on the number yourself could indicate a 'ringer'. The DVLA don't offer a re-stamping service (or much of any kind of a service actually!).
There is no other indication as to the origin of a body-shell apart from this stamped in number.
What a strange situation really, but helpful to those wanting to do shell changes .