When i was 17 i was laying under my 83 F150 yanking the driveshaft to put u joints in.
I undid the 2 u bolts that held the u joint to the rear axle yoke, but the shaft didnt come down.
So i took a hammer and went to town.
Shaft came loose and fell. On my forehead. Other then a small cut and large gooseegg i was fine, im sure though it woulda killed 10 lesser men :p.
But watch placement of ALL body parts.
I forgot one! Similiar situation. I was pulling the driveshaft in my pickup. I wasn't working in my garage. My driveway has a slight slope to it. Pulled the last bolt out. The driveshaft dropped down and my truck started rolling. Set a speed record for fat guy getting out from under a truck. Was able to open the door(I know, not a good idea either) and get it stopped before it made it into my neighbor's yard. Now my truck is blocking the street with the prop laying on the ground. Back under it, reinstall the prop shaft, move the truck back to my driveway. This time I remembered to set the park brake and chock the wheels.