Is there any evidence that 1992-1995 Magnum heads do not crack,
but 1996-2003 Magnum heads do?

EGR keeps peak exhaust temperatures lower. On the 1992-1995 EGR turns on at 60% and off near full throttle. I am wondering if this reduced cracking?

Lots of Dodge Ram OEM catalytic converters developed high backpressure. I wonder if this promoted cracking?

I wonder what Chrysler engineers knew when they designed the very similar 8L V10 cylinder heads around year 1991 with knowledge that these would see a lot of towing duty at higher sustained loads. My fuzzy memory is that they have different exhaust valve seat design with inserts?

There has been discussion here on Moparts of later year non Magnum cylinder head hardened inserts falling out, so Chrysler had design troubles there too.