I'm not sure if Ford Service Glass was available in 1979 for Bolt-Ins. Service Glass is dated year-month it was produced in also. For instance, I have seen a lot of Glue-In Glass dated Mid-70s, like 3A or 5L. Non-Ford Replacement Glass can also always be etched if someone wanted to take the time to create that small of a template. I seem to recall hearing about recently made Glass with etched Carlite logos, but not sure if I recall correctly on that or if they included customer requested Date Codes.