  We consider the possibility of fingerprinting the presence of heavy
additional Z' bosons that arise naturally in extensions of the standard model
such as E_6 models and left-right symmetric models, through their mixing with
the standard model Z boson. By considering a class of observables including
total cross sections, energy distributions and angular distributions of decay
leptons we find significant deviation from the standard model predictions for
these quantities with right-handed electrons and left-handed positrons at
\sqrt{s}=800 GeV. The deviations being less pronounced at smaller centre of
mass energies as the models are already tightly constrained. Our work suggests
that the ILC should have a strong beam polarization physics program
particularly with these configurations. On the other hand, a forward backward
asymmetry and lepton fraction in the backward direction are more sensitive to
new physics with realistic polarization due to interesting interplay with the
neutrino t- channel diagram. This process complements the study of fermion pair
production processes that have been considered for discrimination between these
models.
