Thanks. The Firestone originally had a back per the screw holes but it was missing. The chassis isn't connected directly to line but through a cap and high value resistor. It wouldn't kill you (unless the cap shorted) but you might get a tingle if you were grounded. The way it is now it's as safe as anything. This radio was built before lawyers were invented.
Besides, anybody who really wants to see fireworks can go stick a fork in a toaster!