The 400 is the 351C's big brother, it differs from the 351C in having a 4" stroke crankshaft and a taller 10.295" deck height. It has unique motor mounts and it also normally has a BBF bell housing bolt pattern.
However, a few of them were cast with the SBF bell housing bolt pattern (same as the 351C) in order to allow them to be mated with FMX transmissions. That's why these blocks have become known as "FMX blocks".
A friend of mine has a pair of these blocks sitting in his garage, and would like to sell them. He lives in the mid west. One is a bare block, the other is a complete short block.
I'm going to include a couple of pictures. If you're interested in one of the blocks, PM me and I'll provide you his email.
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