[Porboynz]

I understand that those plugs are removed to clean out the oil galleries after a crank grind. Sadly it seems the replacement plug(s) was not refitted securely and trouble came knocking. At least you now know the cause of the rod bearing failure. Extensive cleaning is now needed for the entire engine to flush out any remaining loose bearing material. The oil cooler needs particular cleaning attention. I had a similar failure and the crank was cracked as a result of the rod bearing failure allowing the rod to hammer at the journal. Good luck with the rebuild.