So gleaning info you put forth,the truck HD engines were known to be put into heaver duty over a cars. So a little more attention was paid to the assembly.
Just as a point interest, this truck had a cooling system filter installed. Not ever seeing a filter like that, I pulled the thermostat and looked in the block.
As expected CLEAN no evidence of rust. I was going to remove it but now will reinstall the filter, with a new cartridge that came in a box with the truck.

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"Hewy"