I replaced the A/C cover fasteners on an 07C210P, and found that there were both well-nuts and riv-nuts used. and not all the same diameter. A couple of the OEM fasteners would not screw in far enough (screw bottomed out on something) so the washers were not held tight and could rattle. After cutting the screws shorter, these screws fastened correctly.
I'm trying to say that you should remove the existing fasteners to access what you have and then get the readily available fasteners to reattach.
2007 Chevy Roadtrek 210 Popular.