  An additional generation of quarks and leptons and their SUSY counterparts,
which are vector-like under the Standard Model gauge group but are chiral with
respect to the new U(1)$_{3-4}$ gauge symmetry, are added to the Minimal
Supersymmetric Standard Model (MSSM). We show that this model is a GUT and
unifies the three SM gauge couplings and also the additional U(1)$_{3-4}$
coupling at a GUT scale of $\approx 5 \times 10^{16}$ GeV and explains the
experimentally observed deviation of the muon $g-2$. We also fit the quark
flavor changing processes consistent with the latest experimental data and look
at the effect of the new particles on the $W$ boson mass without obviously
conflicting with the observed masses of particles, CKM matrix elements,
neutrino mixing angles, their mass differences, and the lepton-flavor violating
bounds. This model predicts sparticle masses less than 25 TeV, with a gluino
mass $\approx 2.3 - 3$ TeV consistent with constraints, and one of the
neutralinos as the LSP with a mass of $\approx 480 - 580$ GeV, which is a
potential dark matter candidate. The model is string theory motivated and
predicts the VL quarks, leptons, a massive $Z'$ and two Dirac neutrinos at the
TeV scale and the branching ratios of $\mu \longrightarrow e \gamma$, $\tau
\longrightarrow \mu \gamma$ and $\tau \longrightarrow 3\mu$ with BR($\mu
\longrightarrow e \gamma$) within reach of future experiments.
