If you could see the mains in person, they look just like the rods to me. ok, well then the mystery is solved on this engine failure, but now the mystery is why the other two engines survived with .002 on both rods and mains. The last build used the same block(without the oil mods), same crank, same rods and the same oil pump and used 20/50 most of their lives. only difference being both other engines had full groove mains and were broke in on 15/40 diesel oil.