[AZKen]

Buy some 1/4" material at home depot (osb or better) and use that to make a template. I did that on an earlier suburban. Drill some holes in it for your fingers. I made the template and installed it with the rubber just like it was glass, to be sure it was correct. Then took to glass shop. Be sure to mark on it that the finger holes are NOT TO BE INCLUDED! Or if you have a loose piece of correct glass make a template from that or give glass to them. Maybe Tony has templates or glass for you. Original glass was 1/4, new glass is 6mm...close enough.
Note: My project (56GMC carryall) was installing all one piece solid windows. No leaky-leaky, no rattle-rattle, no latches needed, tinted, looks cool albeit not orig. Just google 1956 GMC carryall and my Nassau Blue 4x4 will come up and you can see the solid side windows.