Every agent employed by the Kansas bureau of investigation, as defined by Kan. Stat. Ann. §§ 74-4980 and amendments thereto, on the effective date of this act who has completed at least 10 years of participating service with the Kansas bureau of investigation as a member of the Kansas police and firemen’s retirement system on the effective date of this act may elect to receive a prior service credit under the Kansas police and firemen’s retirement system for all service with the Kansas bureau of investigation as a narcotic violation investigator or a narcotics special agent, by filing on or before September 30, 1992, with the board of trustees of the system, a written election to receive such prior service credit. Failure to file such written election shall be presumed to be an election not to receive such prior service credit. Such election, whether to receive such prior service credit, shall be irrevocable. Such prior service credited under the provisions of this act shall not be the basis for credit under the provisions of any other retirement system.