Mont. Code Ann. § 7-2-2513

Persons who are, at the date of the rendition of the decree, the county, township, and district officers or officials and members of the legislature of the county under its former name shall remain in office and shall thereafter be the county, township, district, and legislative officials of the county under its new name and, as such, shall be entitled to the same salaries or compensation during the remainder of their terms of office that they were entitled to receive from the county under its former name.