What specific model engine was this from and what year? Which injection pump? Is this a marine Cummins or a converted truck engine?
I was told by an internet Cummins "guru" that this never happened in boat engines. So seeing is believing.
I also believe that the marine engines are assembled in a different facility than the truck engines. I know that was the case in 1999 when I bought a new one for a repower.
I had a 1991 Cummins in a Dodge pickup and did a fix on mine and several others.
I have also seen many pictures of damage in truck engines similar to yours.
I also know of one guy who went to fix his, discovered the pin was missing and in the oil pan with zero damage to anything. Talk about luck.