So the 1959 Chrysler 300E engine ID starts with MR413. So is this engine from a 300E, or did Chrysler use that designation on other engines? The engine has a single 4 barrel intake and Imperial valve covers. I found a reference on the Imperial Club website saying their Imperial engine was stamped MR413, and nobody seemed to know what that meant on an Imperial engine, since Imperial engines are supposed to start with Y.