“Heated air intake” was never an option in ’71, standard on all engines with one exception, when ordered with the optional “Fresh Air, N96, Air Grabber”. You had one or the other. The driver’s side exhaust manifolds were the same, with mounting points cast for the heat stove. Stove, and all components relating to heated air, was omitted when ordered with N96. Dual snorkel air cleaner, with heated air provisions, on the ’71 383HP, again with only one exception-N96.