I have no specific info on Daytonas but would imagine that stud is similar to those used in air grabbers, a-body hood scoops, 71 Challenger R/T 1/4 scoops. Search for “air grabber stud replacement “ and you’ll find some info. I believe they look like this:
Floyd, i think the stud you show is what is used.
the "washer head" between the course thread that goes into the stud and the fine thread that is used to retain the scoop[s] is just slightly molded into the scoop stud a tiny bit below the plastic surface, or is slightly exposed, having a few slivers of the plastic stud on the mounting side.
this is how i remember the originals being, when i owned my junkyard from 1972-1984/5.
not daytona or super bird scoops, [we never had any of those, or hemi cars] but super bee scoops, a-body scoops, etc. [there were several in the yard during this time] i would imagine all scoops had the mounting studs this way.
