  We present a search for a massive quark (t') decaying to Wq and thus
mimicking the top quark decay signature in data collected by the CDF II
detector corresponding to 2.8 fb^-1. We use the reconstructed mass of the t'
quark and the scalar sum of the transverse energies in the event to
discriminate possible new physics from Standard Model processes, and set limits
on a standard 4th generation t' quark.
