  If left-right gauge theory occurs as an intermediate symmetry in a GUT then,
apart from other advantages, it is possible to obtain the see-saw scale
necessary to understand small neutrino masses with Majorana coupling of order
unity. Barring threshold or non-renormalizable gravitational effects, or
assumed presence of additional light scalar particles of unprescribed origin,
all other attempts to achieve manifest one-loop gauge coupling unification in
SUSY SO(10) with left-right intermediate symmetry have not been successful so
far. Attributing this failure to lack of flavor symmetry in the GUT, we show
how the spontaneous symmetry breaking of $SO(10)\times S_4$ leads to such
intermediate scale extending over a wide range, $M_R \simeq 5\times 10^{9}$ GeV
to $10^{15}$ GeV. All the charged fermion masses are fitted at the see-saw
scale, $M_N\simeq M_R \simeq 4 \times 10^{13}$ GeV which is obtained with
Majorana coupling $f_0 \simeq 1$. Using a constrained parametrization in which
CP-violation originates only from quark sector, besides other predictions made
in the neutrino sector, the reactor mixing angle is found to be $\theta_{13}
\simeq 3^{\circ} - 5^{\circ}$ which is in the range accessible to ongoing and
planned experiments. The leptonic Dirac phase turns out to be $\delta \sim 2.9-
3.1$ radians with Jarlskog invariant $J \sim 2.95 \times 10^{-5} - 10^{-3}$.
