/6 random thrown rod

You probably have spotted the oil pump; it is externally mounted down on the passenger side of the block, back near the bell housing, and the oil filter mounts to it. You remove the 6 bolts on the outer periphery (there are 5 mounting bolts on later ones; don't remove the 5 bolts on the cover) and the pump pulls out; often it sticks pretty good and you have to pry at it. The gear is on the pump; read up on the article on www.slantsix.org about pump gears to see pix of a worn gear.

I only bring it up as the article will tell you that the pump gears are a bit weakish; too heavy an oil on a worn gear could strip it. Then no oil pumps, and the damage occurs. Odd that the guy did not know what weight of oil was put in; I'd be all over that. These days, a lighter oil would be most common, so not the likely culprit but just something to keep in the back of your mind as you go through this. Filter seems more likley.