Okla. Stat. tit. 58, § 58-1006: Inapplication in certain cases

This act shall not apply in the case of wills, living trusts,

deeds, or contracts of insurance or annuity, or any other instrument

wherein provision is made for distribution of property different

from the provisions of this act, or where provision is made for a

presumption as to survivorship which results in a distribution of

property different from that here provided, in all of which cases

the provisions of such instrument shall be given effect.