It isnt very easy or worth it from what I have heard to have the one piece glass, there isnt a "kit" for the 64-66 trucks, there is one for the 67-72 though, you could maybe make one of those work for you, Brothers and One Piece products have them
here is a thread about this also.
http://67-72chevytrucks.com/vboard/s...d.php?t=391948