How much time should glass and body parts predate

[68SSCamaro]

My car was built in Van Nuys 3rd week in January 68. The doors are not original and the windshield was replaced. The 1/4 glass is dated VZ-10 (Dec 67) and the rear glass is dated NX-10 (Jan 68). I found another 01C car in a salvage yard that had an earlier VIN and the driver's door glass and the right 1/4 were VZ-10. A 01D car I saw at Pomona had NX-10 driver's door glass and I know of a 01B car with the same date. This is the data I used to find dated door glass for my car. Windshield data is hard to get.

If you're serious you need to look for cars from the same month and assembly plant.

Martin