Thanks for the welcome's.
The casting broke off from each bolt. The bolts were still attached to the engine, but the idler was laying down under the fan once the car was stopped. The power steering belt was also off, but it was in one piece. There was no squealing, just a big Bam when it broke off. Then the check engine light came on, and there was no power steering. The engine itself sounded fine.
We thought that it might have been from the engine rebuild, but the mechanic said that he didn't know how it could have happened.
Should I still ask the question in the other forum? I don't want to ask the same thing all over the place.