[Zoom This]

Originally Posted by COBRA406

Was the number you gave located on the timing cover or on the passenger rear
side of the block under the head? Never seen a casting number on the
blocks like this one. As you probably know Clevelands were only made for
4 years from 69-73. 351M/400 production started with the 400 in 71. The
351M from 75 on. Basically same heads (2V) on all of them. 4V heads unique
to Clevelands. M blocks have 429/460 bellhousing pattern, Clevelands pattern
same as W motors. M blocks taller and wider than the Cleveland but share most components except intakes, crank, rods and pistons. I'll dig into my
manuals if you need to know exactly.

The number was located on the block just behind the starter.