Electronics Box Hinges....

The reason I think there are nuts behind them is because they spin when I turn them. Alo the over head electronics box has the same hinges with a different stopping angle and are through bolted with nuts on the back side
 
They are through bolted. I was able to get my fingers in between the panels and hold the small nut to remove.
 
Jump on ebay if you need em. Dirt cheap. Replaced mine last year and exact replacement.