A bstract We explore the sensitivity of W and Z boson production in hadronic collisions to uncertainties in parton distribution functions (PDFs) at large x arising from uncertainties in nuclear corrections when using deuterium data in global QCD fits. The W and Z differential cross sections show increasing influence of nuclear corrections at high boson rapidities, particularly for the d quark, which is diluted somewhat in the decay lepton rapidity distributions. The effects of PDF uncertainties on heavy W ′ and Z ′ bosons beyond the Standard Model become progressively more important for larger boson masses or rapidities, both in pp collisions at the LHC and in scattering at the Tevatron.