Here's the VIN tag on our 63 Polara 500.
I havent looked at it for ages but looking at this pic (taken by the previous owner, 6 months before we bought it) it appears the spot welds (if that's what it had) have been drilled, so it may now be stuck on. You can see it is positioned so the number is viewed from the outside of the car, as Dodge330 said.
And our fender tag has cross-head screws. It looks like someone's unscrewed it, or has tried to, but the engine bay still has the original paint, so I guess they're the original screws. Looks like it was glued on too, before it was painted?