There was even a "351/400" engine, not too sure what the difference was in that. I had one in a '79 Lincoln MK-V. It was terrible, no power at all...but at least it used a ton of gas!
No difference, there never was such a thing. Ford made the ID tag for the LH valve cover with both engine family names on it ("351M/400"), hence the confusion.
All 335-based blocks in the Lincoln Mark V were 400's, including the CA and special order 400's made in 1977. Same applies for the 4-door and 2-door Continentals.
No one has since reported taking one apart and finding a Windsor crankshaft and the taller pistons of the 351M, so unless someone swapped the block on one of these (or someone discovers one of Ford's infamous substitutions), they're all 400's in the Lincolns.
It is very unlikely that your Mustang has a 351M. It would be a transplant and they would have to replace the transmission as well.
Not true. Though most 351M/400s came primarily with the big block bellhousing pattern, 1973 editions of the block came cast with both patterns and starter holes for the small-block transmission bellhousing.
The 351M/400 generally has different engine mount drillings as well, but I believe the 351C mounting locations are available to drill out.
Funny - nobody has taken the above opportunity to build a 400C. Too much work when the 460 is around, I assume.
That, and "400C" sounds like a Chrysler luxury barge.
-Kurt
