Align the front to back and then get the bottoms flush. If the top still sticks out, open the door and use a 2x4 as a pry bar to tweak the top of the window frame in. If you stand the board up and put the bottom of the board through the window on the inside. Now you can push on the board and it will push the top of the window frame in toward the cab. Go slow until you get it where you need it....
