There is at least one exception to the use of a single snorkel air cleaner on C bodies equipped with 440 standard engines besides certain years of T&Cs, and that is the Dodge models. Dodges with standard 440 engines all got the dual snorkel air cleaners largely because most 440 equipped Dodges went to police use, and for plant simplification, all 440s on full size Dodges got the dual snorkels. I can't say exactly which years this was the practice since I haven't had enough cars with this setup over a lot of years but I believe it was the practice for at least 1970-1973.
I am not sure if the same practice was used for Plymouth models or not but such models as the 1970 Sport Fury GTs with the 440 standard engines being the only ones available besides the 6 bbls, did get the dual snorkels standard too.
