it aint the poly mounts, they do have movement, so you aint rigid there. if you have 12 pt. cage ,you have frame connecters, so you are solid there. body could fly off and i dont think it would cause that. i think it would have to have had a violent reaction to end up there.pinion angle , drive shaft or u joints are about all i can come up with. i could have been stressed when it was in the other car and broke on lucky you.good luck hope you find it fast before the cha-ching machine gets turned on high.