not sure if it's been mentioned or not but Chrysler did offer an over the counter dual quad set-up for rb engines. it was the 385hp 413 set-up with a cast iron single plane intake and two small afb's. chrysler never had the money to r&d and market a lot of combos for production the way gm and ford did. in the '60's most enthusiast were leaning toward single carb technology that was developing. this was basically born out of nascars ban on multi-carbs, and let's face it; most people can't work on one least wise two or three. i have far more problems with the single four on my stock '69 r/t than the dual quads on my '65 coronet.