The Model A "diamond block" is sort of in line with the AA truck engines.
Diamond blocks are characterized by a small cast in "diamond" near the valve gear cover, and are engines which were made "post Model A era" for industrial uses.
Vince Falter covers this extensively and not necessarily complementary...
https://www.fordgarage.com/pages/diamondblock.htm
Think combines, stationary power plants, welders, air compressors.
Considered by some to be "improved" over the Model A engine, my experience is they're about the same - and not necessarily worth paying "extra" for.
They can be found without numbering in the number pad which MAY give them value to someone attempting to "match" frame numbers. But the number pad of most any engine can be "ground down" at least once to remove the previous markings, and re-numbered to one's heart content.
The Model B engine can fall into this same category - but B engines can have their own special failings, including valve seat/deck cracks, and issues with the heads.
If you want bulletproof, there is always Burtz - but given time even these will be found to have "weaknesses."
Joe K