Mont. Code Ann. § 72-3-316
Will from place where probate unprovided for
72-3-316 . Will from place where probate unprovided for. A will from a place which does not provide for probate of a will after death may be proved for probate in this state by a duly authenticated certificate of its legal custodian that the copy introduced is a true copy and that the will has become effective under the law of the other place.