A new procedure proposed recently enables one to start from the quark and lepton mass and mixing data at the low scale and construct mass matrices which exhibit simple SO(10) structure at the SUSY GUT scale. We elaborate here on the numerical details which led us to an SO(10) model for the quark and lepton mass matrices that explain the known quark data at the low scale along with the observed depletions of solar- and atmospheric-neutrinos. We also apply the procedure to a second scenario incorporating the solar-neutrino depletion and a 7 eV tau-neutrino for the cocktail model of mixed dark matter but find the SO(10) model deduced in this case does not exhibit as simple a structure as that observed for the first scenario.

26 pages, FERMILAB-PUB-94/061-T and OSU Preprint 286