. Do any of you know?
Yes, LOL
As Special Ed would say, "thats just the way it is" LOL
Its not necessarily a mustang/shelby thing as far as the striker. The bolt head markings match what we see for NJ production at time. Late NJ cars would have phosphate RBW bolts at striker, that fastener wasn't used at AO Smith. As far as hood latch obviously AO Smith attached those as they have the phosphate anchor bolts.
Best evidence of who did what is found at hood hinges where you see the RBW holding hinge to body and anchor holding hinge to hood.
I'm sure I can find some pictures if you give me a little time
note:since you said KRs is why I mentioned the RBWs. Early cars would have typically had anchors on striker/hood hinges
hope this helps