i would think if some one put the engine togather right with enough clearance from the rods to block and torqued everything right it did't hit the block.that would be a rookie mistake.the only why the rod makes contact with something is the main caps broke or block,or crank but that's rare.if the piston broke there wouldn't be the big contact spot because aluinium woulnd't do that to steel and no marks on the small end of rod.so does it come down to the roller lifter broke and pined between the rod and the block on down stroke and pulled the rod apart then the other bolt hit.the bearing in the pic don't have anything to do with it.the bearing slide after the rod was contacted.the rod was number 2,4,6,8.i will have more info if you take pics of cam and lifters.jeff