Some time go, I found a bolt in my driveway and I assumed someone working on my house at the time had dropped it. Fast forward to this weekend, and I'm investigating a rattle by looking under the rear of the vehicle. I see these two threaded holes on some structure (I'm not a car guy) on the driver side aft of the rear tire. I don't know if not having these bolts in place is causing my rattle, but it seems like threaded holes should have bolts in there. Thoughts?