1972 Duster Build with my Daughter

That number is the vin sequence number. It matches the last 8 in your vin. There is one other like it on the trunk weatherstrip rail too. Its not a numbers matching thing. Its a vin matches the body thing.
There’s a high probability I’ll probably drill out the rest of the spot welds and switch the upper radiator support so it will look like the original 72 at first glance. I just left it connected for now to ensure the side radiator supports weee square and spaced properly. Get it all aligned in tact in the way it is then switch it