I picked up a truck tall deck block this summer. When I had it mag checked for cracks right after I picked it up I noticed it had MARINE cast in the bell housing by the part number. Did not think much about it until this weekend. Went to do some busy work to get rid of flash in the lifter valley and do some clearancing for the stroker crank and the block is much harder then my last one.
Could the MARINE mean it is a higher nickel block? It is noticably harder when cutting with a carbide rotary tool bit.