I had a carrier bearing go out on me not long ago, thought it was the exhaust knocking until i took a left hand turn and something sounded like it was going to rip the car apart. I took hold of the front of the driveshaft and started flopping it about. The housing itself snapped clean in half, only thing i can figure is having it jacked up caused the rear to drop and put pressure on it. I'm just glad it didn't decide to venture downward and hit the fuel line.