Ford's 2.9l and 4.0l heads had a tendency to crack when over heated, just once
3.0l didn't have that issue, but...........
Heat causes metal to over expand, which is why head gaskets blow from overheating, the metal ring, between head and block, sealing the cylinder gets crushed.
And because of the over expansion any head can crack.
Yes, aluminum expands 7 times faster than metal(cast) so have to be careful with aluminum heads