  SO(10) grand unification accommodates intermediate gauge symmetries with
which gauge coupling unification can be realized without supersymmetry. In this
paper, we discuss the possibility that a new massive gauge boson associated
with an intermediate gauge symmetry explains the excess observed in the diboson
resonance search recently reported by the ATLAS experiment. The model we find
has two intermediate symmetries, $SU(4)_C \otimes SU(2)_L \otimes SU(2)_R$ and
$SU(3)_C \otimes SU(2)_L \otimes SU(2)_R \otimes U(1)_{B-L}$, where the latter
gauge group is broken at the TeV scale. This model achieves gauge coupling
unification with a unification scale sufficiently high to avoid proton decay.
In addition, this model provides a good dark matter candidates, whose stability
is guaranteed by a $Z_2$ symmetry present after the spontaneous breaking of the
intermediate gauge symmetries. We also discuss prospects for testing these
models in the forthcoming LHC experiments and dark matter detection
experiments.
