NASHVILLE, Tenn. — 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, Rosanne 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.