this Mach 1 was also the first one released and second one produced out of all three Mustang assembly plants with these features.
read the whole story https://www.hotrod.com/articles/rare-find-first-1969-ford-mustang-mach-1-ordered-super-cobra-jet-v-8-drag-pack-4-30-gears/
https://www.youtube.com/channel/UCRGiFDEn6naVP1UQSeViIdQ for his videos
and a look at the hundreds of articles he's done at Hot Rod
Jerryheasley@gmail.com if you have a barn find or know of one.
Or call him at 806-236-3681.
He will feature you in the video and/or buy the car, or pay a finder's fee if you don't own the car and just know where it is, etc.