Many years ago, Dad and I were changing the rear leaf springs out on our '79 Burb, on the driveway. Had the rear axle on a jack(lifting /swapping one side at a time) and the body lifted on another jack. We were swapping to 3/4 ton units with an extra overload, on a C10....He was moving the new spring into place and something got jostled, damn Burb came off the jack and landed on the drum with him still partially under it ....he moved but not quite fast enough. Scared the livin crap outta both of us, seemed like it took me an eternity to get the truck jacked up so he could get out. I think now that he probably cracked his collarbone or shoulder blade, took him a few months to get full use of that arm without pain. Of course he wouldn't go to the ER....