Original answer:
it really doesn't stand for anything, its just an "m" people think that it stands for modified or some of the others and that's fine, but in reality its just an "m" nothing more nothing less
Additional answer:
There is a casting code of MCC common to most 351M/400 engines. The code stands for "Michigan Casting Center." Many who know this believe the M stands for Michigan. I agree with the previous poster that Ford Motor Company does not officially call the M code engines by any other name; however, the M likely originates from the casting foundry name, as it does with the 351C and 351W engines.
Note that many refer to the 351M as a 351 "modified" presumably because the M engines share components with the 351C and 351W. Of course, the designation "modified" could apply to many engines produced by any of a number of automakers, as many new engines are derived through some modification of an existing engine. So it is extremely unlikely that engineers at the Ford engine group would call a new 351C/W hybrid "modified."
Population of Midland is about 42,000.
midland
midland
The address of the Midland Genealogical Society is: Po Box 2421, Midland, MI 48641-2421
The address of the Midland Experimental Aircraft Assoc is: Po Box 2464, Midland, MI 48641-2464
The web address of the Midland Center For The Arts - Hall Of I is: http://www.mcfta.org
Midland, Texas is 1,266 miles according to Google Maps. Midland, North Carollina is 502 milles. Midland. Michigan is 363 miles.
The address of the Midland Childrens Museum Inc is: 5212 Huntington Drive, Midland, MI 48640
The phone number of the Midland Center For The Arts - Hall Of I is: 989-631-5930.
The address of the Midland Center For The Arts - Hall Of I is: 1801 W Saint Andrews Rd, Midland, MI 48640-2656
19 miles on US-10.
729 miles