Written notice of changes desired in existing labor contracts required

In the case of all existing labor contracts, agreements or understandings which do not provide for at least a sixty-day notice of desired changes and which contracts, agreements or understandings terminate after seventy days following the effective date of this act, the parties thereto shall nevertheless inform, in writing, the other party or parties of any specific changes desired to be made in said contract, agreement or understanding and file a copy of such desired changes with the State Board of Mediation at least sixty days before the date fixed for the termination of said contract, agreement or understanding. In the case of labor contracts, agreements or understandings terminating within seventy days after this act shall become effective, the parties thereto shall forthwith, or not later than ten days after the effective date of this act, inform the other party, in writing, of the specific changes desired to be made in said contract, agreement or understanding and promptly file a copy of such demands with the State Board of Mediation.