I'm fresh out of leads in figuring out the missing hardware pictured -- three "holes" with inserts that look like they should take some sort of fastening hardware, missing when I bought it (sorry for the sideways close up photos... that's how they uploaded). The attached diagram shows Item 2A: “Fasteners” (4B3807739), and Item 33: “Retaining Plate Receiver For Radio-Wave Clock Pop-Rivet” (N 90659001). But the inserts don't look like they take pop rivets, and that seems counterintuitive since the bumper needs to be removed for belt work.

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The Audi dealership says that they couldn't identify what was needed to put something in the three missing spots -- mine appear to have wear marks from hardware, but Audi's line was that it could be hardware intended for the A6 that doesn't translate... Can someone with installed fasteners let me know what they might be? Thank you in advance!