No sarcasm, just trying to get off the semantic sidetrack of "how", due to my choice of one word, and back to "what"... as they are factory, or at least "Ford" IMHO.
On Jeff's note of a stamping error, I thought of that as my cars are 6 days apart, but I don't think so.
I have pictures of a '65 and other 68's with the same holes (or very, very similar as exact measurments are hard to get). I have a guy with a '67 big block and a '67 small block saying he has the same holes. And another '68 or two here in Oz with them. Out of the few replies with photos I got to queries, the majority show these. Indeterminate on others, as some of the replies here in Oz were right hand drive conversions which means serious firewall surgery, so they were removed from the sample. They are hard to spot unless the engine and trans are out and you are looking from a very low angle, required a mirror-on-a-stick for my running auto car. So not something the average photos would show.
I am unsure of plants for all, as noted mine are both Dec 67's San Jose builds, not sure of date/plant stamps on the panels.
So it does not seem a shhort term stamping error. Or related to engine, as it is on big blocks and small blocks (not sure about any 6's). I have an auto and a manual, so does not seem realted to transmission. Its not console, as neither of mine had one. Or AC as mine don't have that option either. And it sits way to high, as far as I know, or can tell from the FAM's and other references I have, for brakes or fuel. And no electrics there as far as I know....
Its not a large sample, actually very very small, but with what I am seeing it is not "uncommon" as most of the good photos I have are showing them, or very similar, which would seem to indicate some factory or dealer commonality. As to me the odds of a number of PO's doing the exact same thing seems a bit of a long shot.
Some sort of buck/locator for some purpose at the plant, similar to the paint dolley marks? Locating the sheet metal for welding??? Maybe done on "some" cars and not others for
reason???
I really don't know and thought the concours crowd may know, or have an interest in finding out what these are, as it seems a bit of a mystery, and not uncommon.
All I am trying to do is determine what these are, and in asking around I am finding more and more cars that show very, very similar holes that do seem factory... with nothing in them. I'm just becoming very curious as to why they are there...