Haven't heard of that happening. Sorry to hear that. Have heard about diff. mounts coming loose from the frame but most of those were from being loose and the torque played a part on that. That one reason we always say "check all the suspension and component mounting bolts for correct torque". You say the bottom or lower right..front or rear? Did the wheel or a-frame catch hard on anything like a stump or rock? In any case they should be able to be welded.