I don't see L5 listed as a registered manufacturer of bolts. I didn't look for F yet but perhaps one of you gentlemen already know that and perhaps neither is still a functioning manufacturer?
By the same token, 5 isn't a recognized manufacturer either?
The flat washer used with these is a captured split lock washer?
Does the 67 GT500 hold the all time record for the most unique, obscure, and limited quantities manufactured of any modern US car?