Thanks for the additional pictures.
As we continue to try to restore our cars to more accurate standards, I believe we all can agree that correct NOS and/or clean restored dated coded parts along with the correct hardware are what separate the exceptional cars from the nice cars. And exceptional 1st Gens are not always ultra rare ZL1s, Yenkos, and JL8s, but include all original 6-cylinders well done with neat family histories.
My hope is to find other U79 and/or AM/FM radio survivor cars that still have the original hardware and attempt to discover some commonality on hardware used based on the plant and build date. This research is not limited to only radio ground straps, but includes all the hardware used on our cars. I realize that more than one suppler supplied many of the various hardware pieces on our cars, and the assembly line process was not perfect; mistakes and variation was common and to be expected. But if we can discover from survivors and original cars that one or several hardware markings appear to be common for a build period, we can then only "assume" that a certain head marking(s) to be correct.
Keep the pictures coming along with your plant and assembly build date!