Gov't Mule wanted to include guest vocalists on songs for its coming album "Shout!," but the rockers didn't want to minimize any outside contributions. They're maximizing them instead, with a two-disc collection featuring two versions of every song on the album. The first disc features vocals by Gov't Mule frontman and guitarist Warren Haynes. The bonus disc offers interpretations of the songs by singers including Elvis Costello, Ben Harper, Dr. John and Dave Matthews, whose version of "Forsaken Savior" premieres today on Speakeasy, alongside Haynes' take.

"It seemed a waste to have singers of this stature only sing a small part of the song," Haynes told Speakeasy. "So the idea quickly became, let's have them sing the whole song."

Gov't Mule wrote and recorded "Forsaken Savior" as a tribute of sorts to Levon Helm, the former drummer for the Band, who died in 2012.

"Levon was a close friend and someone I had played with many, many times. He was a musical hero of mine since before I ever knew him," said Haynes, who first met Helm in the early '90s. "The song wasn't about him, it was just written and recorded in a way that paid homage to the Band and that music. When we were looking for the right person to do the alternate version for the bonus disc, I thought about Dave."

More specifically, he thought about Matthews' occasional collaborations with Emmylou Harris, especially their version of "The Long Black Veil."