Johnny Cash's sideman Marshall Grant dies in Ark.

NASHVILLE, Tenn. (AP) - Not all pioneers know exactly where they're going, and that was definitely the case for Johnny Cash & The Tennessee Two.

Cash, guitarist Luther Perkins and bassist Marshall Grant - the last surviving member of the group who passed away Sunday morning at age 83 in Jonesboro, Ark., after an aneurysm and stroke - changed the future of American music and popular culture with their distinct boom-chicka-boom beat.

Grant fell ill after rehearsing for a concert to raise funds for the restoration of Cash's boyhood home, said Cash's daughter, Roseanne Cash.

Grant always freely admitted the soon-to-be historic trio had no special insight as they shaped that universal beat - a sound that launched a million imitators with songs such as "I Walk the Line," "Folsom Prison Blues, "Ring of Fire," "Big River" and "Cry Cry Cry."

"Our inability had more to do with our success than our ability did, and I'm not ashamed of it," Grant once said in an interview.

That statement pierces the heart of just why Cash, Perkins and the steady - both in rhythm and in life - Grant were so special.

Grant and Perkins were auto mechanics in Memphis, Tenn., who practiced together at the shop when their co-worker Roy Cash introduced them to his brother, John, in 1954. They quickly realized all three couldn't play acoustic rhythm guitar, said John Rumble, senior historian at the Country Music Hall of Fame and Museum in Nashville.

So Perkins, who died in 1968 from injuries suffered in a house fire, borrowed a Fender Telecaster with volume controls stuck at wide open, Rumble said, and Grant bought a Kay bass. The resulting sound - The Johnny Cash beat - was both simple and driving, and there from the start.

"Luther played the way he did because he couldn't really play any way else," Rumble said. "That very sparse, plowing rhythmic sound was something they just fell into. They didn't just sit there and work on it for weeks. That's pretty much the way they started out."

After initially failing to impress Sun Records producer Sam Phillips, the trio passed a second audition and began recording in 1955 on a roster that included Elvis Presley and other proto-rockers such as Carl Perkins. They earned modest success quickly and built on it with appearances first on the Louisiana Hayride and eventually the Grand Ole Opry.

In time, that simple rhythmic pattern would infiltrate everything. And though Cash's name was out front, there was never any doubt where that sound that helped launch rock "n' roll and modernize country music came from.

"The Johnny Cash sound was created by the three of them equally, you know what I mean?" said Rosanne Cash, Johnny Cash's daughter. "There was none of that "boom chicka boom' without Marshall. You can't separate the three of them at that point when it all started. It was one thing. You know, they're united again, the three of them."

Rosanne Cash spent the last days of Grant's life at his side in Arkansas, she told The Associated Press in a telephone interview Monday afternoon. They reconnected last Wednesday at rehearsals for a Johnny Cash Festival appearance that served as a fundraiser to help restore the late singer's boyhood home in Dyess. Johnny Cash, born in Kingsland in south-central Arkansas, died in 2003.

Rosanne Cash said Grant, who lived in Hernando, Miss., fell ill while in Jonesboro and the Johnny Cash Festival was held Thursday night without him. It attracted country music stars George Jones and Kris Kristofferson.

Grant played bass with Cash until 1980 when he began a career in management, handling The Statler Brothers until they retired in 2002 and later writing the autobiography "I Was There When It Happened." Grant and Perkins were among the first inductees into the Musicians Hall of Fame in Nashville in 2007.

Not only did the trio almost singlehandedly spawn rockabilly, a rich vein of rock "n' roll that's mined today by stars such as Jack White and Brian Setzer, it helped popularize rock and modernize country music.

That sparse sound was perfect for rock "n' roll, Rumble said, and eventually became part of the DNA of country music, a genre Cash would revolutionize, then symbolize for 40 years.

"It was a highly influential sound," Rumble said. "You had the standard 2/4 beat, the Ray Price shuffle and the Johnny Cash beat, and between those three that covers a whole lot of ground in country music."

Through much of that time, Grant was by Cash's side. Rosanne Cash argues that without Grant, you could forget about most of it - no rockabilly, no "Man in Black," no legend.

"He wouldn't have gone where he did without Marshall, and therefore this lineage not only of me but of the next generations of roots and rockabilly and country musicians would've disappeared," she said. "An entire generation of those musicians owe something to Marshall."

Arkansas State recently acquired Cash's boyhood home and sponsored last Thursday's concert to benefit its restoration and the establishment of a museum in the Dyess Colony.

Johnny Cash was born at Kingsland in southern Arkansas and grew up at the Dyess Colony, where during the Depression the government offered to support Delta farmers by funding homes and hospitals in return for their working the surrounding cotton fields. The experiment faded by the 1950s as the post-war boom attracted farmers to the cities.

Part of the 2003 movie "Walk the Line" about Johnny Cash was filmed in Dyess.