Hello Gang; I seem to remember that the cross ram or dual induction, as I have also heard it called perhaps incorrectly, was available with any big block RB engine from a 361 to a 413. It was also available on in Plymouths, Dodges, and Chryslers, stock in some models and as an option on others. It isn't really unthinkable that an Imperial could be ordered with the dual induction since they were well optioned cars stock and money was no object for many of their original buyers. Allegedly there were some 57' and 58' Imperials build with a Chrysler 300 engine, and that was entirely different animal from a regular 392. In the case of a cross ram engine if the only real differences between that and a regular 413 was the manifolds, carburation, and cam, then it would be quite easy to build an Imperial with this setup even on the production line. Best Regards Arran Foster 1954 Imperial Newport Needing a Left Side Taillight Bezel and other trim parts.