Michigan Compiled Laws, Chapter 500. Insurance Code of 1956 § 500.140

Sec. 140. Any insurer heretofore formed or incorporated under any insurance law of this state, whose act of incorporation or act under which formed was repealed by Act No. 256 of the Public Acts of 1917  1 or is repealed by this act  2, shall continue to have a corporate existence (if a corporation) or existence (if other than a corporation), and shall have all the rights, privileges, immunities and limitations, obtained under such acts of incorporation or formation, as evidenced by their articles of incorporation, bylaws, power of attorney or constituent agreements made pursuant to such acts, as existing at the time this act takes effect; except, that all amendments to such articles of incorporation or powers of attorney or agreements shall be made hereafter in compliance with the provisions of this act, and all such insurers shall be otherwise governed by the provisions of this act. All reincorporations of such incorporated insurers, for the purpose of extending their corporate existence or for any other purpose shall be made only in compliance with this act, and any incorporated insurer heretofore incorporated under any insurance law of this state may reincorporate under this act.