The civil service system existing on July 6, 1945, in any county to which this part shall become applicable upon its passage, shall be continued in force and effect under the terms and provisions of this part, without any change in the rights, privileges, duties, benefits, or liabilities upon the part of any person or body, except to the extent that the terms and provisions of this part make such change. In other words, such previously existing civil service system shall be absorbed and continued into the civil service system provided by this part, with no changes of any kind to be made except to the extent that this part differs in its provisions from the provisions of such previously existing civil service system. As respects the county board of health and the board of registrars, which, in the only county to which this part shall be applicable forthwith upon its passage, have not heretofore been subject to a civil service system, there shall be allowed a period of six months in which to organize and prepare for the administration of the personnel system herein provided for the boards, and during such period of six months the employees and appointees of such boards shall continue in all respects under and subject to the laws to which they are subject on July 6, 1945. When any county or municipality or appointing authority hereafter becomes subject to this part, a period of six months shall be allowed in which to organize and prepare for the administration of the personnel system herein provided for, and during such period of six months the employees of such county, municipality, or appointing authority shall continue in all respects under and subject to the laws which they are subject to at the time such county, municipality, or appointing authority becomes subject hereto.