i mean, think about what they came in: trucks (mostly) and what gets abused more than work trucks? more likely to neglect OCI and maintenance? (*coughs* besides rental equipment *coughs*)
the "flaking" of cam bearings has also been (loosely) linked to the acid/acid by products in modern motor oils, namely synthetics-- which again, goes to extended, missed or ignored OCI's.
so, little wonder the cam bearings are pooched in a lot of magnums.