In 1971, Duane Allman swerved his motorcycle to avoid rear-
ending a flatbed truck in Macon, Ga., and was fatally
injured—leaving behind a 2-year-old daughter. Today, that
daughter, Galadrielle Allman, 43, is co-producer of "Skydog: The
Duane Allman Retrospective"—a seven-CD set due Tuesday from
Rounder. The box is as much a musical biography as it is a
daughter's attempt to understand a father she never knew.  "This
project turned out to be a more complicated story than I
expected when I started 13 years ago," said Ms. Allman from her
home in Berkeley, Calif. "My dad wasn't some phenomenon who came
out of nowhere. This box really documents a hard-working and
earnest session musician who was searching for a new sound while
he earned a living."  Duane Allman John Gellman  Duane Allman,
of course, is best known today as the guitarist who founded the
Allman Brothers Band in 1969 with his younger brother Gregg on
lead vocal, guitar and keyboards. Before his death at age 24,
Allman's vision launched a new country-b