We search for evidence of resonant top quark pair production
in 955 pb-1 of p anti-p collisions at s**(1/2) = 1.96 TeV recorded with
the CDF II detector at the Fermilab Tevatron.  For fully reconstructed
candidate tt-bar events triggered on leptons with large transverse
momentum and containing at least one identified b-quark jet, we compare
the invariant mass spectrum of tt-bar pairs to the expected superposition
of standard model tt-bar, non-tt-bar backgrounds, and a simple resonance
model based on a sequential Z' boson.  We establish upper limits for
sigma(p anti-p --> Z') . Br(Z' --> tt-bar) in the Z' mass interval
from 450 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 tt-bar is
found to be less than 0.64 pb at 95% C.L. for M_Z' above 700 GeV/c2.