Can't help you, chum if you don't believe what I'm telling you. Holley R4668 carbs were put on Roadrunners with heated air intakes like I mentioned in a previous post. Mine never came with that option so I got the Carter AVS. Typical numbers found on broadcast sheets are fine for statistical purposes but they do not describe the rules for putting which carb on which car. FSM does.
Actually the broadcast sheet had nothing to do with statistics, it told the line workers what actual part to install on the car.
But I've only been following, researching, cataloguing and collecting information about 71 Plymouth B bodies specifically for about 25 years now. You're probably right and I'll stop incorrectly trying to help you.
