Transitions into the doubly excited Na-2 1 (3)Sigma(g)(-) state have been analyzed using near-dissociation expansions (NDE) to represent the vibrational energies and inertial rotational constants, while the centrifugal distortion constants were held fixed at "mechanically consistent" values calculated from the Rydberg-Klein-Rees (RKR) potential implied by those G(upsilon) and B-upsilon functions. The input data cover the range upsilon = 0 to 57 and N up to 47, and the fit yields upsilon(D) = 61.41(+/- 0.10) and D-0 = 3385.70(+/- 0.2) cm(-1).