Over thirty years at the desk of his very own late-night talk show, multiple generations of fans, the respect of comedians the world over: David Letterman has had, by any measure, an awfully good run.

As with many illustrious careers, Letterman’s humble early shot followed even humbler, earlier shots. Just above, you can hear the 21-year-old “Dave Letterman”’s broadcast from April Fool’s Day 1969 on WAGO-AM, the closed-circuit radio station he helped to found at his future alma mater, Ball State University. Though only a five-minute clip, this recording showcases not just Letterman’s preternatual microphone presence, but his way with the near-psychedelic walls of sound effects, seemingly free-associative speech, and pure wackiness that so came into its own in the late sixties and early seventies. (The Firesign Theater would soon perfect it.) Letterman followers who must know everything — and they certainly exist — should note that, when he calls a delirious-sounding woman in this segment, he calls none other than Michelle Cook, the very first Mrs. Letterman. Though we have yet to learn the identity of Letterman’s Late Show replacement, I feel certain, after this listening experience, that the Letterman of twenty years from now will rise from the ranks of podcasting. Listen out for him; he may not drop colorful phrases just like “horse dentures falling into a rusted howitzer artillery shell,” but you’ll know him when you hear him. Or her.