Johnny Cash Waylon Jennings
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Country Rewind: Johnny Cash + Waylon Jennings Cover Kristofferson in Classic 'Letterman' Appearance

During a 1985 appearance on Late Night With David Letterman, half of country supergroup the Highwaymen honored bandmate Kris Kristofferson when Waylon Jennings joined Johnny Cash for a performance of "Here Comes That Rainbow Again."

What began as a performance by Cash with a backup band featuring the likes of future Country Music Hall of Fame inductee Marty Stuart and Letterman's musical sidekick Paul Shaffer turned into a duet between the Man in Black and Hoss.

Cash's appearance promoted his Chips Moman produced 1985 album Rainbow, which came out the same year as The Highwayman album, a collaborative effort starring Cash, Jennings, Kristofferson and Willie Nelson. Rainbow's track list included another Cash and Jennings duet, "You Beat All I Ever Saw."

The Cash and Jennings collaborative album Heroes followed in 1986 and found two cornerstone solo artists singing Cash's "Field of Diamonds," Eddy Raven co-write "Folks Out on the Road," Troy Seals co-write "I'll Always Love You (In My Own Crazy Way)," Kristofferson's "Love is the Way," Bob Dylan's "One Too Many Mornings" and Rodney Crowell's "I'm Never Gonna Roam" and "Even Cowgirls Get the Blues." Good stuff, even if it's not held on high by vinyl record collectors.

Each opportunity for Cash and his wife June Carter Cash to work with Jennings and Jessi Colter as performers or songwriters was more than just a wise business decision.

"Those guys really loved each other," Waylon's son Shooter Jennings told Rolling Stone in a 2016 feature about The Highwaymen Live - American Outlaws box set. "Because they all came from the same ilk and knew each other and made a career together, they were all close friends. That's where the magic was. It wasn't an awkward pairing or like working with someone they didn't know."

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Jennings also crashed Letterman's interview that night with Cash, opening up discussion about both superstar vocalists' struggles with addiction and their stint as roommates in the Nashville suburb of Madison, Tenn.

Cash spoke of "a period of my life when the only person that would talk to me is the Lord and the only woman that would have me is Betty Ford" after bragging about the biscuits the "Big River" singer cooked for himself and Jennings while living in Madison.

Now Watch: The CBS TV Movie Starring The Highwaymen is Currently on Amazon Prime