  We consider a model in which the third family fermions are subjected to an
SU(2) interaction different from the first two family fermions. Constrained by
the Z-pole data, the heavy gauge boson mass is bounded from below to be about
1.7 TeV at the $2\sigma$ level. In this model, the flavor mixing between $\tau$
and $\mu$ can be so large that $Br(\tau\to \mu \bar{\nu_\mu} \nu_\tau)/
Br(\tau\to e \bar{\nu_e} \nu_\tau)$ and $Br(\tau\to \mu \mu \mu)$ provide a
better constraint than the LEP/SLC data in some region of parameter space.
Furthermore, flavor-changing neutral currents are unavoidable in the quark
sector of the model. Significant effects to the $B^0-\bar{B^0}$ mixing and the
rare decays of the $K$ and $B$ mesons, such as $K^\pm \to \pi^\pm \nu {\bar
\nu}, b \to s \nu {\bar \nu}, B_s \to \tau^+\tau^-, \mu^+\mu^-$ and $B_{s,d}
\to \mu^\pm \tau^\mp$, are expected.
