  We discuss a model in which the third generation fermions undergo a different
$SU(2)$ weak interaction from the first two generation fermions. In general, a
flavor changing neutral current interaction is expected. Constrained by the
precision low energy data, the mass ($M_{Z'}=M_{W'}$) of the heavy gauge bosons
is bounded from below to be about $1.1$ TeV for $\alpha_s=0.125$ and about
$1.3$ TeV for $\alpha_s=0.115$, at the $3\sigma$ level. This model favors a
larger $R_b$ and a smaller $R_c$ as compared with the Standard Model, but it
does not explain the $R_c$ data. If one takes the $R_b$ data seriously, then
$M_{Z'}$ is bounded, at the $3\sigma$ level, to be $462$ GeV $< M_{Z^{\prime}}
\cos\phi < 1481\,\, {\rm{GeV}}$, where $\cos\phi$ is the mixing angle between
the two $SU(2)$'s in the model. Effects predicted for high energy experiments
at the Tevatron, LEP140, LEP-II, LHC, and future linear colliders are also
discussed.
