Bob Dylan and Johnny Cash could’ve been one hell of a duo.

And for two days of lighthearted recording sessions, Feb. 17-18, 1969, they were one hell of a duo.

Just released on Travelin’ Thru, 1967-1969: The Bootleg Series Vol. 15, a three-CD set credited to Bob Dylan (Featuring Johnny Cash), those sessions demonstrate how the reluctant spokesman of a generation and the Man in Black are completely simpatico even as the music falls apart, the tracks stop short and Cash constantly calls for a gopher to bring lyrics sheets to help the pair get through numbers they barely know.

Whether they’re captured laughing their way through the only known Dylan version of “Wanted Man;” hilariously yodeling across a pair of Jimmie Rodgers medleys; singing reverent spirituals; playing “Matchbox” with Carl Perkins, who wandered in from a session in the next-door studio; or singing “Girl From the North Country” on the Ryman Auditorium stage for “The Johnny Cash Show,” Travelin’ Thru illustrates the world’s loss at Dylan and Cash’s inability – or unwillingness – to turn their collaboration into a product that was releasable at the time.

Better late than never, as they say. And as is so often the case with Dylan’s Bootleg Series releases, this one shines a light on the high-quality material he left in the vault. As loose as they are, and even though the rockabilly arrangements scream Cash and only whisper Dylan, these outtakes are utterly delightful.

Later, when Dylan attempts solo versions of “Ring of Fire” and “Folsom Prison Blues” with a band that includes Charlie Daniels on bass and guitar, respectively, he turns them into fully realized Bob Dylan songs in arrangements that signaled the sound of Slow Train Coming, a full decade ahead of its release.

Culling music from the sessions that produced John Wesley Harding, Nashville Skyline and Self Portrait, Travelin’ Thru focuses most heavily on the Dylan-Cash partnership, which comprises half the music; however, Dylan and band are all by their lonesome laying down Harding and Skyline outtakes in ’67 and ’68, respectively, on disc 1. Meanwhile, the back half of disc 3 finds Dylan running through a handful of bluegrass numbers, including the Carter Family’s “East Virginia Blues” and Dylan’s own “To Be Alone with You” with Earl Scruggs on recordings for a PBS special.

Travelin’ Thru is yet another side of Bob Dylan (lowercase) and one that was worth the wait even if the pangs of missed opportunity echo through the decades-old recordings.