wow ,sorry to hear that.hope he gets well soon .txarc ,i had this happen to me when i was 16,i was pulling the tranny and did exactly what you said ,shook it off the pins and the stands were unsteady .car dropped on me and broke both arms and sternum.i was lucky,i guess.i put my arms up too stop the fall on me ,didnt work ,i came out looking like edward scissor hands.Be careful guys ,o also dont use scissor jacks either.