Quarter window upper stop bracket, fits all 1971-73 Mercury Cougar and 1971-73 Ford Mustang coupe or convertible models. This is the smaller of the two stop brackets, and it installs towards the back of the window. There is a decent illustration of the quarter window installation in the Osborn Body Assembly Manual. One stop bracket per side, right and left are the same.
Ford part number D1ZB-6529968-A.