Two days ago when I started the engine a very, very loud metallic noise came on - sounded like two pieces of metal moving in opposite directions grating on each other.

The noise disappeared when I put the tranny in any of the drive positions. But it came on again when I switched to PARK or NEUTRAL, and, again, disappeared when in a drive gear. The car drove O.K. but when I stopped and put it in PARK, it started again.

Yeserday, the noise had disappeared entirely! I'm just keeping all fingers crossed that it won't return - but I wonder if any other member had similar experiences, or might be able to talk about the possible cause.