  The mixing of a new $Z'$ boson with the $Z$ significantly improves the fit to
the LEP precision electroweak data, provided that the $Z'$ couples mainly to
quarks. If $M_{Z_2}<200$~GeV, the $s$-channel $Z_2$ production and
$(W,Z,\gamma)Z_2$ pair production cross sections at the Tevatron give an excess
above QCD of $b\bar b$ and $(W,Z,\gamma)b\bar b$ events, respectively, with
invariant mass $m(b\bar b)\approx M_{Z_2}$, which provide viable signals for
detection of the $Z_2$. The interference of the $Z_2$ with $\gamma,Z_1$ in
$e^+e^-\to \bar bb(\bar cc)$ at LEP\,1.5 energies is correlated with $R_b(R_c)$
and may be observable.
