Duane Allman ( November 20 , 1946 â `` October 29 , 1971 ) was an American musician and lead guitarist of the southern rock group , the Allman Brothers Band . Howard Duane Allman ( November 20 , 1946 â `` October 29 , 1971 ) was an American guitarist , respected session musician and the primary co-founder of the southern rock group The Allman Brothers Band .