I don't think the crank out windshields had anything else supporting the window. There are rubber cushions on either side but thats about it. Do you have the interior trim off? I know when I removed my trim there is an area on the windshield posts where it looks like the roof section is bolted to the lower part of the cab at the factory. Check out http://www.oldchevytrucks.com to see if they maybe have a manual for your truck.