Learned a great lesson working on the Spitfire. You know they had very little ground clearance. I was replacing the exhaust system and had the car up on four jackstands. One bolt was tough and I needed a little more leverage, so my foot searched out something to push against. All of a sudden one of the jackstands went clattering out across the floor and the car was teetering back and forth on the other three.
I got out of there REAL fast!!
Ah... the memories of working on my old Spit. I got so good at changing out a rear-end half axle that I could complete the job in under 30 minutes.