My note: Oh man this clip shows why Letterman is/was the best. He *actually* cared about the bands and let the bands actually play. This X album was a huge fave of mine (still is). They perform songs from the great album “More Fun in the New World” produced by Ray Manzarek (The Doors). Must be from around 1983.
BTW, X reunited with original lineup to play at SXSW in 2014.
PS Saw X on 40th anniversary tour with original line-up in San Francisco in 2015.