Check for a stamped number on a machined pad on the block just ahead of the passenger's side cylinder head. There should be a letter code suffix that will give you a pretty good idea of the year of manufacture and the application of the engine. 400's were mostly used in big Impala station wagons and a few pickups, also the van-front class B motorhome chassis. There was a heavy duty version of the 400 with 4-bolt main bearing caps, which was really scarce.
Jerry

Last edited by Hotrod Lincoln; 03/13/2011 3:28 AM.
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