OK.That long aluminum? bar is the frame from the vent window assembly.That nut holds the frame and that strap?rusty looking piece with the bolt thru it.All the bolts are tight.If I hold the frame of the vent window it moves back and forth just a little,The rusty strap is stationary but the frame is wider than that piece so the frame moves.Should the strap,Rusty piece,be tight against the frame as to not let it move,like mabey it is welded or glued to the vent window frame....Or is the slight movement of the frame normal..

I hope this helps....