Thanks Tim. I have since found a photo on Mar-K's site that shows that the hole goes through the bed's angle strips...Seems odd that Chevy would have put this hole where they did??? Mar-K replied to my question by telling me that they (Mar-K) don't punch the hole in their new angle strips because the new hole might not align with their customer's old bed sides. They do however, punch the hole when they weld the new strips onto their new bed sides.
Thanks for the photos.
Jim