Sec. 3. This Act shall not repeal Articles 6229 to 6243, both numbers inclusive, of the Revised Civil Statutes of Texas, 1925, as amended by Acts of 1933, Forty-third Legislature, page 206, Chapter 94, but the provisions of said Articles 6229 to 6243, as amended, shall not apply whenever a city or town as provided in this Act shall formulate, devise and adopt a pension plan according to the terms and provisions of this Act.