Well first I would read that report, very informative. But I can tell you that as a 30 year LOF/Pilkington employee there are some small mistakes in it.
Today GM can and do open contracts to other companies for Market tests and we have grabbed a few contracts over the past "8" years they have been doing it. They did not start doing that until this century. Back in the sixties LOF Rossford Ohio and Lathrope Ca. had the windshield, backlite and doorlite contracts for all Camaros. We had all doorlite glass for the Firebird. PPG had the windshield and backlite glass for the Firebird. I think in 69 PPG got some of the Camaro also. All LOF aftermarket glass was stamped LOF and used no other name. I believe PPG had some aftermarket names none of which are Shat R Proof
As someone who has monogrammed about 4 million pieces of glass back when we still sandblasted them on I can tell you the first example shown is a double struck piece of crap that couldn't have been repaired and in no way comes close to an OEM windshield. The second shows too much wear in the positive as the letters and #'s are filling in. Not OEM quality but ok for AGR. The third shows fade out top to bottom on the blasting, although by 60's standards passable for OEM not great. So I have seen 3 poorly monogrammed pieces of glass, screams AGR to me. But don't take my word for it I only do it for living ! Another detail missing is the LAMINATED part of the stamp. The Sat r proof should also have a laminated stamp on it required by GM for OEM glass.
Even if LOF or PPG were on strike during any of that time we are required by GM to increase our inventory dramatically when our contracts come up to cover labor disruptions and either company could probably pick up short term slack on top of that.
Lastly do you not think aftermarket installers back in the day couldn't put in a windshield as well as the factory ? Every car on a new car lot today visits a local body shop for touch ups that you can't tell are there.
Anything else you need ?