1. Election. A beneficiary entitled to a disability retirement benefit under section 1122 of the former retirement system law, as in effect immediately before July 1, 1977, may elect to be governed by this article instead of the law applicable to the disability retirement benefit that the beneficiary is receiving.
2. Manner of election. The election under subsection 1 must be made by written application to the chief executive officer within 6 months after adoption of this article by the participating local district.
3. Effect of election. If the election under subsection 1 is made, this article shall apply from the date of the beneficiary's original eligibility for disability retirement, but any increases in benefits may only be granted from the date of election.