Don't suppose we'll ever know for sure what happened. The shop naturally wasn't courious enough to spend time and man-hours to unbutton the engine to find out.
I'm still faulting the oil pump. It was suggested a head gasket but there wasn't any water in the cylinders nor had the coolant or oil mixed with each other. Though the engine did heat up the radiator didn't. For it to lock the way it did had to be a bearing seizure or rings or pistons melting to cylinder walls in my humble opinion. The reason nothing was heard was the windows were down, the radio was on.........loud and the boy's mind was on this goooood lookin' babe sittin beside him. Its that old tree falling in the forest thing. It still makes a sound but there's just no one there to hear it.
Hopefully the salvage engine will last $900.00 worth.