I found these two screw type things in the back plastic tray area where the soft top goes down into. I've cleaned and used 303 in that entire back area several times over the years and these were not there before. I have no idea where they came from or what they are...

Anyone?

 

look at the rear tray area, there are going to be 2 holes, 1 on each side. These "stoppers" go there and are secured by a nut on the backside.

 

Thanks for pointing me in the right direction. I ended up finding it in the manual, and am perplexed by this design that requires these screws to have a bolt on the other side instead of just a plastic push in clip like the rest of the back tray. And you can't access this unless you remove panels from inside and not from the rear trunk area.

What's got me even more boggled is that there are two of the push in clips missing as well (shown with a red dot in the pic below). There's never been any work done back there either. Looks like I have another weekend project to find those missing nuts. Crazy thing is this started because I'm replacing the passenger regulator, and the one door panel clips was stubborn and then shot across the car in the back. I didn't find it and realized the back soft top tray has two open spots on the sides for things to go down into. I wonder what treasures lie buried beneath...