Keith and others; The cross ram manifold and carb'd assy was only on the wedge engine family ( ...350 / 361 / 383 / 413 and 426's ... ). Of these engines only the 413 was chosen to power the Imperials. I did not include the 440 since it was never offered from the factory with dual 4 bbl carbs. The late model Chrysler 331 ( 300 hp ), 354 ( 340 & 355 hp ) and 392's ( 375 & 380 hp ) could be purchased from the factory with a dual in-line four bbl'd carb assy. With either a direct special order or a later dealer prep'd request it was possible for an Imperial owner to have the higher optioned engine under the hood. This higher horse powered engine was commonly known as the "300 engine". The '56 341 ( 320 hp ) and '57 345 ( 345 hp ) De Soto engine's also had a in-line 4 bbl'd manifold option. I included the De Soto info 'cause they look like the Chrysler / Imperial V8 and they will bolt up to the same transmission. The standard '56 De Soto engine was 330 cubes. The 2 bbl version had 230 hp while the 4 bbl was 255 hp. Food of thought if you are hurting for a '54 to 56 Chrysler 331. And they are lighter. Rodger & Gabby Colo Spgs '47 De Soto Custom w/passenger door mounted swamp cooler '63 Le Baron w/ std A/C '66 Le Baron w/dual A/C