Thanks for all the ideas and input. Unfortunately i need it running for work, until this weekend. Il pull the pan and see whats going on. Gonna pull and inspect the pump first. Then pull the main caps one at a time starting with the center one. If the crank is moving enough under load to cause this, shouldnt one side of the thrust surface of main bearing show a lot of wear? Ive seenthat on alot of sb chevy engines on rear main bearing. But usually they had a ton of hard mileage and were in manual trans equipped vehicles.