The DeSoto and Dodge 270/315/325 poly used similar head architecture but was not related to the Plymouth A Engine, using its own heads and the same bottom end as the Dodge and Desoto Red Ram Hemi.

This engine has a bore of 3.875 in (98.4 mm) and the common 3.3125 in (84.1 mm) stroke, and was used in the following vehicles, amongst others: The 318 is the most common version of the A engine, produced from 1957 through 1966 in the US and 1967 in some export markets when it was replaced in all markets by the LA 318.

A high-performance version called the V-800, offered in 1957 and 1958, used two four-barrel Carter carburetors to produce 290 hp (216 kW), making it the highest-output factory A engine.

Bristol Cars introduced the 318 in the Mark II model of their 408 (in 1965) and continued to use it in the succeeding 409 and 410 until 1969.

Its actual piston displacement is 325.25 cu in (5,330 cc) but it was marketed as a 326 to avoid confusion with the Dodge Red Ram 325.