MY OPINION: the nut on rod bolt has not been touch.I can see where the cap has moved up and down in till the bolt on opposite side broke.I don't like to point fingerprint but it looks like builder error.improper torque or bolt not seated right,maybe both???
About a city block Drove it to a car show on Sat, ran great. Sunday I fixed a short in the gas gauge and then took a trip around the block.Didnt make it. Will dismantle engine this week to look at other damage.