How to replace a driver's or passenger side window glass and vent glass assembly on a 1951 to 1955 Chevrolet 3100 pick up truck. The same demonstration for the 51-55 Chevy truck might work for a 1947-1950 Chevy 3100 as well. After removing a few glass assemblies, I recommend that you take the door off first. The benefits of taking the door off gives you a little more leverage and room to maneuver the glass window out of the door and off the track. Also, these older trucks have a lot of cab noise and additional noise from the doors themselves. Since you have the door off and the old glass out, before putting the new glass in, you can either spray a few coats of undercoat inside the door and/or you could spray some expandable foam insulation. Both help reduce noise. Just make sure you do not spray the expandable foam on the interior components of the door or within the pathway of the door glass when it is rolled down. To make the doors shut easier and quieter, change the weather stripping as well.