  We present recent developments in the diagnostic study of heavy gauge bosons
at future $pp$ (CERN LHC) and $e^+e^-$ (NLC) colliders with the emphasis on the
model independent determination of gauge couplings of $Z'$ to quarks and
leptons. The analysis reflects a complementary diagnostic power of the LHC and
the NLC (c.m. energy 500 GeV, integrated luminosity 20 fb$^{-1} $). At the NLC
for $M_{Z'} \sim 1 $ TeV {\it all } the quark and lepton charges can be
determined to around $10-20 \%$, provided heavy flavor tagging and longitudinal
polarization of the electron beam is available. At the LHC primarily the
magnitude of three (out of four) normalized couplings can be determined,
however typical uncertainties are by a factor $\sim 2$ smaller than at the NLC.
