hmmm.... I have a few of the 372046 types, but neither car had these at that location.
The FAM shows a hole with a plastic pin type clip, simialr to the ones just to the right of the pic noted on page 153 (with no part number, just tho the left of the blue tab and Wiring label on the page) not the metal S. But no relative size or reference. It seems the pic is 351C engine wiring, which could be bigger than that for the single wire for the fuel feed.
I guess I can use the S type ones I have for now and keep researching...
No one has pic of an original '68 showing this detail (San Jose, Dec build if relevant)?