[DeTomaso] Cleveland block identification?

[Jerry Knotts]

A friend of a friend has found a stash of older used engines.  He asked 
me how to tell the difference between a 351C and a 351M or 400.  I was 
stumped.  The engines are mostly together and been setting for quite a 
while.  Is there an easy way visually to tell the difference.  My mental 
micrometer is not good enough to tell the difference in deck height 
between blocks and I can't see inside to compare the water boss height 
and shape.  Is the casing number of "D2AE" sufficient to differentiate 
the blocks?


Thanks in advance,

jerry knotts