[Ziggster]

Cast irons are weaker in tension than steels. They are brittle with virtually no ductility and thus are prone to sudden breaking. In any failure, typically there are multiple factors that contributed it as opposed to just a single factor. Looking at the pic in post #2, it seems the thickness of the wall of the bell housing is realitively thin. Also these blocks are now very old, and over time may have been subjected to their fair share of "abuse", perhaps leading to hairline fractures making them predisposed to breaking. From what I've seen, the factory Ford engine stands were designed to support these blocks at both the front and rear. There were likely several reasons, and probably one was a weakness in the bell housing area. So I see contrinbuting factors as such:

1. Thin casting
2. Only partial casting of bell housing leading essentially to 100% tensile loading with no compressive loading
3. Hairline fractures
4. Heavy block to begin with

I just recently went with a home brew exhaust flange support for my engine stand, as there was no way I would ever think of supporting my C59A block using the bell housing for two main reasons.

1. Safety of life and limb
2. Multiple thousands invested

Pretty simple decision I think.