The concert "We Walk the Line: A Celebration of the Music of Johnny Cash" will now feature performances from Willie Nelson and Sheryl Crow .  They've just joined the lineup that already included Ronnie Dunn and Jamey Johnson .

The concert is part of the year-long celebration of what would have been Cash's 80th birthday.  It will take place at Austin City Limits Live at The Moody Theatre in Austin, TX on April 20.

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