Today on the way onto the freeway, I hear a clanging as though something were falling out of the engine compartment. I looked back into my rear view mirror and found that there was something bouncing onto the road surface. I had to drive a couple of miles to get back onto the freeway entrance again. But there was the distinctive alternator pivot bolt in the middle of the road. I grabbed it and sure enough mine was missing. I had thought that maybe it was a wrench or socket that I had left under the hood. I carefully drove home and reinstalled it. Whew! Glad nothing else bad happened. I still need to look closely to make sure the bolt did not crack or damage the timing cover.