The Ram Air/400 H.O. engine are one and the same other than bolt-on accessories. So why have two model designations if your theory is correct? Ram Air III has the same heads as the H.O.

I am not saying any of the invoices are "misprinted". I am saying that broadcast copies carry codes, not text, based on the ordered RPOs. The car is built by the broadcast copy to the RPOs ordered, not what any invoice states in text.