[Unreal]

Chuck,
I probably don't know all the differences between a 69 bracket and later ones, but the holes you mention are one of them. The originals do not have any holes in the bottom. Also, the originals had a square nut which was projection welded to the bracket. The one above has a hex nut. I can't see the pics well enough to tell if it was projection welded , or arc welded. I think (not absolutely sure) that some of the newer ones were arc welded.

There are others, as well. I had one with a square nut and the small holes on my car, but thanks to KevinW, I'm putting a correct on on my car as soon as I get it painted.