1960 rear bumper question.. wrong one?

[Leinhit]

I just purchased This rear bumper from summit and it just got delivered yesterday. I'm not sure it's right for my 1960 stepside.

I think what is throwing me off on the rear fender you can see what looks like a body line or rust line from an old bumper that wrapped around almost to the tire you can see two holes in the fender behind the rear tire that I assumed were bolts going through to the bumper.

Am I wrong about this and the bumper I received is actually the correct one? What would be the line on the rear fenders with the two holes on both sides?

Thank you