I was driving my car a heard a boom then pulled to side of the road when i barely give my gas i hear a clunking grinding noice from rear and its like the car i pulseing foward at first i thought that one of my rea wheels was about to fall off but all lugs were tight so i cruised home in my drive way. When i put it in park in the drive way the car kept roling back so i parked it in the garage on leveled ground with the car idleing and in park to reverse with car standing still i hear grinding and from reverse to drive i hear clunk grinding