  We calculate the two loop contribution to the predictions of the mass scales
in an SO(10) grand unified theory. We consider the modified unification scale
boundary conditions due to the non-renormalizable higher dimensional terms
arising from quantum gravity or spontaneous compactification of extra
dimensions in Kaluza-Klein type theory. We find the range of these couplings
which allows left-right symmetry to survive till very low energy (as low as
$\sim$ TeV) and still be compatible with the latest values of $\sin^2 \theta_W$
and $\alpha_s$ derived from LEP. We consider both the situation when the
left-right parity is broken and conserved.We consider both supersymmetric and
non-supersymmertic versions of the SO(10) theory.Taking the D-conserved
non-susy case as an example we calculate the effects of moderate threshold
uncertainties at the heavy scale, due to the unknown higgs masses,on the
gravity induced couplings.
