Okla. Stat. tit. 60, § 60-175.37
Death of trustee - Appointment of successor
Upon the death of a sole or surviving trustee of an express
trust and in the absence of the trust providing for a practical
method of appointment, the power to appoint a trustee shall vest in
the court having jurisdiction thereof, and on petition of any person
interested such court shall appoint a successor in whom the trust
shall vest.