69' convertible window curtain date stamp

[stichn]

I noticed quite an extensive article on date stamping for hard glass but was interested in what is supposed to be on a convertible plastic window.  If anyone has photos it would be a huge help.  I have tried several top manufacturers and none of them are willing to date stamp a window or they don't have the stamp.  Al Knoch does Corvette but they say they don't have the Camaro tooling.

Thanks,