i posted this some in the talk section but the v6 guys need to check this out. i noticed at most a month ago the rubber ring from the crank pulley was looking tattered,( 1st pic) but yesterday it came apart.(2nd pic) if you run your car hard at all, better check your pulley. i was lucky and made it home but it would be a real bummer on the side of the road as it could cause some serious and dangerous problems and its not a easy fix. the pulley is so deep in the frt, most pullers dont work...

2005 Mustang 4.0 V6 crank pulley failure