So I found this bumper for my 73 to replace my old beat up bumper but it has some holes along the sides. Any one know what they are for? It looks to me like they were used for some sort of trim.

Any help would be greatly appreciated
Thanks

This is a picture of the bumper with the holes in question circled in red.

 

That was the optional deluxe bumper that had a rubber edge guard. Probably never find that rubber reproduced or NOS.