  If the top is very heavy, m_t >> M_Z, the dominant radiative correction
effects in all electroweak precision tests can be exactly characterized in
terms of two quantities, the rho-parameter and the GIM violating Z -> b bbar
coupling. These quantities can be computed using the Standard Model Lagrangian
with vanishing gauge couplings. This is done here up to two loops for arbitrary
values of the Higgs mass.
