Mont. Code Ann. § 32-1-448

Any bank doing business in this state may pay any money remaining to the credit of a deceased depositor or deliver any personal property in its possession belonging to such deceased depositor to an administrator or executor of such depositor duly appointed and qualified in another state, provided no demand therefor shall have been previously made by an administrator or executor appointed in any county of this state, and such payment shall discharge the bank making the same from its liability on account of such deposit.