Okla. Stat. tit. 60, § 391

Any gift, testamentary or otherwise, of any property whatsoever to the State of Oklahoma and a county within such state and a city or town within such county (all of which, including the state, are hereinafter referred to as "governmental units"), shall be construed as a gift of such property to the named governmental units as tenants in common; and, unless other proportions are distinctly specified in the instrument by which such gift is made, shall be construed as conveying an undivided one-third (1/3) interest to each of such governmental units. Laws 1953, p. 291, § 11.