NEW YORK — David Letterman has marked three decades in late-night television with one of his favorite guests.

Letterman had Howard Stern on his CBS late-night show Wednesday.

They congratulated each other on age improving their looks.

Then Letterman proved it by displaying a picture of them from when Stern first appeared on the then-NBC show in May 1984. Letterman had a bushy head of hair. Stern had a mustache.

Letterman says Stern’s old picture “looks like a guy who was on to talk about a career of writing bad checks.”

The “Late Show with David Letterman” airs weeknights at 11:35 p.m.