Round eye grill slot paint detail

[RedRoad]

Just watched an old commercial for 75 trucks with a detail Ive never seen before. Much like the 60-66 hood paint the small holes in the filler valance are painted a mat black to make them look like a large slot. The change in paint detail they mention I thought was the headlights going from black eyes to argent but not certain.

Any one know if this was just pre release paint detail axed before production or have they all just worn off over the years like the GMC paint? Paging Keith...Keith S needed for truck line question

GMC pic for reference.

Promotional video

https://youtu.be/QuqiVHF58RQ?t=592