We search for the production of a heavy W-prime gauge boson that decays to third generation quarks in 0.9 fb-1 of ppbar collisions at sqrt{s} = 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron collider. We find no significant excess in the final-state invariant mass distribution and set upper limits on the production cross section times branching fraction. For a left-handed W-prime boson with SM couplings, we set a lower mass limit of 731 GeV. For right-handed W-prime bosons, we set lower mass limits of 739 GeV if the W-prime boson decays to both leptons and quarks and 768 GeV if the W-prime boson decays only to quarks. We also set limits on the coupling of the W-prime boson to fermions as a function of its mass.