  We study some of the consequences of the SU(6)$_{L}\otimes$U(1)$_{Y}$ model
of unification of electroweak interactions and families with a horizontal gauge
group SU(2)$_{H}$, paying special attention to processes with flavor changing
neutral currents. We compute at tree level the decays $K^{+}\longrightarrow
\pi^{+}\mu^{+}e^{-}$, $K_L^0\longrightarrow \mu^{+}e^{-}$ and $\mu^{-}
\longrightarrow e^{-} \bar{\nu_e} \nu_\mu$ from which we obtain lower bounds
for the mass of the horizontal gauge boson associated with FCNC. Finally we
obtain limits on the mixing between ordinary and exotic charged leptons.
