  We search for evidence of resonant top quark pair production in 955 pb-1 of
p-pbar collisions at sqrt(s)=1.96 TeV recorded with the CDF II detector at the
Fermilab Tevatron. For fully reconstructed candidate t-tbar events triggered on
leptons with large transverse momentum and containing at least one identified
b-quark jet, we compare the invariant mass spectrum of t-tbar pairs to the
expected superposition of standard model t-tbar, non-t-tbar backgrounds, and a
simple resonance model based on a sequential Z' boson. We establish upper
limits for sigma(p-pbar to Z') times Br(Z' to t-tbar) in the Z' mass interval
from 450 GeV/c2 to 900 GeV/c2. A topcolor leptophobic Z' is ruled out below 720
GeV/c2, and the cross section of any narrow Z'-like state decaying to t-tbar is
found to be less than 0.64 pb at 95% C.L. for M(Z') above 700 GeV/c2.
