Found them at a really good price in Florida 4 years ago, guy took them off a 350 in a 57 chev and put on the good running 1406 Edelbrock in their place. He just wanted to get rid of them and clean out his garage.
Just about stole them. My cousin when I was 15 years old had a 65 GTO with the 3 Duces, can still remember him opening up the secondaries on that one when going for a ride, Powerful Experience.
Keeping these on hand to honor that memory, that was the start of the muscle car era for me.