Upon retirement of a local safety member or a local miscellaneous member for industrial disability, if the member is totally disabled he or she shall receive in lieu of the allowance otherwise provided by this article a disability retirement allowance equal to 75 percent of his or her final compensation plus an annuity purchased with his or her accumulated additional contributions, if any.
For purposes of this section, “totally disabled” means inability to perform substantial gainful employment and the presumptions
contained in Section 4662 of the Labor Code shall also be applied to the determination of total disability.
This section shall not apply to any contracting agency nor to the employees of any contracting agency unless and until the agency elects to be subject to the provisions of this section by amendment to its contract made in the manner prescribed for approval of contracts, or in the case of contracts made after January 1, 1974, by express provision in the contract making the contracting agency subject to the provisions of this section.