It seems a bit of super-early Metallica—audio, at least—has turned up on the interwebs.
It's a recording of the band performing December 18, 1983, at Cleveland's Agora—almost a year away from Ride the Lightning.
The Ecstasy of Gold (Ennio Morricone)
Hit the Lights
The Four Horsemen
Jump in the Fire
Fight Fire With Fire
Ride the Lightning
The Call of Ktulu (Early version called "When Hell Freezes Over")
Seek & Destroy
(Anesthesia) Pulling Teeth