A general analysis of the vector-boson decay modes of the nucleon in N = 1 supergravity unified models is camed out using the full set of W-gaugino, gluino, and 2-gaugino dressing diagrams of LLLL and RRRR dimension-five operators. It is shown that the third-generation effect with a heavy top quark (m, 240 GeV) leads to an enhancement of the vector-boson decay modes Tp and To and a relative suppression of VK* modes in domains discussed recently where TT modes dominate the TK modes of the nucleon decay. The parameter space where these enhancements mcur is numerically investigated and is found to be non-negligible. Branching ratios and partial lifetimes for the decay modes for a class of models are given.