Home Jambase Jason Isbell & The 400 Unit Debut Allman Brothers Band Cover In...National Music NewsJambaseMusicJason Isbell & The 400 Unit Debut Allman Brothers Band Cover In SeattleSeptember 13, 2017225FacebookTwitterPinterestWhatsApp Rockers Jason Isbell & The 400 Unit worked up a cover of an Allman Brothers Band song for last night’s show in Seattle.