PSA's agreement to buy Opel and its UK Vauxhall business from GM for 2.2 billion euros ($2.3 billion) led to union fears that German factories could be axed as the combined PSA-Opel moved to reduce excess capacity.
On Wednesday, PSA CEO Carlos Tavares pledged to continue all Opel's collective agreements when he met German government and union officials.
Ruesselsheim currently builds the Insignia and Eisenach makes the Adam minicar and Corsa subcompact, according to Automotive News Europe's Guide to European Assembly Plants. The Mokka X is built in Opel's plant in Zaragoza, Spain.
Opel said in the release it was changing its legal status into a limited liability GmbH from its AG joint stock company form as a step toward the automaker's European businesses being grouped into one company, then merged with PSA.
The changes to the legal entity will be completed in the second quarter, Opel said. All co-determination rights of the employees will remain unchanged, the company added.
The closing of the agreement between GM and PSA that will trigger the integration of Opel/Vauxhall into PSA is subject to various regulatory approvals, including the clearance by the European Commission, Opel said.
Reuters contributed to this report