[tateos]

My bad holes were very obviously different from my good holes. The good ones snapped really hard when they broke loose and the holes and bolts were dry. The bad ones were wet with coolant (I think). They was a slimy - and silvery coating - it was almost like anti-seize compound on the bolt threads. I think only one of them was completely stripped, but I drilled and inserted them all. I don't recall seeing any powdery aluminum - maybe I missed it.

I have given this a lot of thought, and I think (just a theory - just an opinion) the head gaskets let go first, allowed coolant & exhaust gases into the bolt holes and that degraded and corroded the aluminum to the point where the bolts let go, and the exhaust then entered the cooling system in a big way.