I have done this a couple of differant ways. I'll try and explain the beast I can. First you will of course have to cut lexan to fit opening. It must have a metal holder[chanel] that it is secured in. With your window in the down postition take a strap and attach to the botton metal piece attached to window. have it long enoungh to come up through the same opeing as window. Attach a screw,bolt,etc. in the center of the the window opening about 2 inches from the bottom of the window opening. Let the strap you attached to the bottom of the window attach[slip over] the screw,bolt ,etc. You can unbutton the strap and pull up on window at this point. Once you get window closed you can again have a hole in strap to secure window. I got the idea from some Old over the road trucks that were done this way. You can also weld a bolt to bottom of window channell. Cut a straight slot in door from top to bottom to where the welded on bolt will go up and down in slot. Put a thumb screw on it[bolt to secure in upright postion. Cheesy but it works. I'm sure I did not explain this to where it sounds as simple as it is.