Mich. Comp. Laws § 32.831
The retired status of officers, warrant officers and enlisted personnel previously retired under the provisions of Act No. 84 of the Public Acts of 1909, as amended, being sections 32.1 to 32.85 of the Compiled Laws of 1948, shall be continued under the provisions of this act, but the rate of such retirement pay shall not be increased or decreased because of the provisions of this act. The deductions made from retirement pay by evidence of federal retirement as provided in section 49c of Act No. 84 of the Public Acts of 1909, as presently or subsequently established shall remain the same and shall not change the retirement pay received from the state. Personnel of the military establishment who, on the effective date of this act, have been members of the national guard or defense force or both for a period of not less than 15 years, shall receive service credits earned and shall continue to accrue credits for retirement purposes under the provisions of Act No. 84 of the Public Acts of 1909, as amended, which requires 10 years of actual duty service. Retirement compensation of warrant officers and enlisted men shall be computed in the same manner as retirement compensation of officers notwithstanding the provisions of section 49 of Act No. 84 of the Public Acts of 1909, being section 32.49 of the Compiled Laws of 1948. Those persons who have not had 15 years service with the national guard or defense force on the effective date of this act shall not continue to accrue service credits toward retirement under previous legislation unless they are full-time employees of the state military establishment as provided in this act.
MCL 32.831