The hood scoop is certainly interesting for sure. With no known example of a Deuce having come equipped with one, and only the pictures of the 6 cylinder prototype car you've seen here to go on, it's really a difficult item to do much further research on. I do feel however, that it is likely a Dixco piece, going solely on the design of the integrated tach.
I can understand where the "Hurst" connection comes into play, as the open end version of the scoop was also installed on a few hundred Hurst-prepped Jeepster Commandos, like this one.
Hurst Jeepster
Here's a side view of another H-Commando.
Side View
While the AMC Rebel Machines were also prepped by the folks at Hurst that hardly makes the scoop a "Hurst" piece. It also doesn't explain the scoop appearing on a prototype Deuce that was built long before the actual 9010 COPO cars were ever assembled and shipped to Canonsburg. So we can hardly credit Hurst for giving Yenko the idea to use it, but that also doesn't necessarily help us with sourcing it's manufacturer.
My guess is that the scoop was a Dixco item based on the fact that it integrated their existing hood tachometer design, and that Yenko may have tried one on the prototype Deuce simply because a plain flat Nova hood was about as mundane as it got for the musclecar era. They were likely more expensive than the standard stand alone hood tach and would have been considered for an extra cost option like the Dixco underdash gauges, racing mirrors, and thick rim sport steering wheel.
Yenko obviously carried and installed Dixco instruments on their post-69 vehicles, and also had their hood tachs custom silkscreened by Dixco, which makes me think the scoop may have been an early design that Yenko was aware of and was considered for use on his new project.
Now why there isn't some old Dixco promotional material on these scoops floating around somewhere escapes me. You'd think even if they were a "discontinued" design or something that was produced even in limited quantity for the aftermarket, there'd be a few NOS examples floating around
somewhere that we could examine.
I do know for a fact that Dixco had several other "designs" in mind for their hood tachometers, one of which included a 2 guage set-up integrated right into the face flanking the tach needle sweep. Promotional materials were printed and distributed, however I've never seen or heard of an actual example being produced. Perhaps the hood tach scoop was another still born design that was picked up exclusively by Hurst, who later added it to their Rebel and Commando projects? But that doesn't explain Yenko's using it first.
Are there any Hurst or AMC guru's out there who can comment on the scoop being installed on the Rebel Machines? Was it AMC or Hurst's idea to include the scoop?