It's not that they are cracking a cylinder because of overheating it's because of blowing a head gasket. The 6.2's and still the 6.5's are susceptable to overheating in the military. The 6.5's are better suited for military and non military use.
They will crack between the cylinders with Extremely excessive heat but excessive heat is the bane of these engines. The water crossover kits only permits water to get to the thermostat in a less restrictive state IMHO, Ok maybe a little water will crossover.