I would suspect that you have a bad catalytic converter, when the catalyst inside breaks into pieces, the rattle like a can of rocks, and the pieces are often times in this business refered to a bricks. If you can safely raise and support the vehicle try tapping on the catalytic converter with a rubber mallet and see if you can duplicate the noise that you are hearing.
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Monday, March 24th, 2014 AT 6:34 PM