Things are looking up for Ssangyong.

Korea’s smallest auto maker plans to put back on the payroll 455 workers who have been on unpaid leave since the company was declared bankrupt and placed in court receivership in 2009.

Ssangyong subsequently was acquired by Indian auto maker Mahindra & Mahindra in February 2011 for $463.6 million.

Ssangyong spokesman Sutaek Hwang confirms the 455 workers will return to work March 1 at prevailing pay rates under an agreement signed with the auto maker’s union.

Management emphasizes that 159 workers who were dismissed for cause during and after a fractious strike in 2009 will not be rehired. Another 1,900 employees who accepted Ssanyong’s voluntary-retirement offer in 2009 also will not be rehired.

Hwang notes that during the three-plus years the workers have not been on the payroll, the auto maker nonetheless has continued paying for their social-insurance policies, including medical insurance.

Ssangyong also has given the workers an amount sufficient to pay their school-age children’s tuition costs, Hwang tells WardsAuto.

The auto maker currently has 3,500 blue-collar workers on its rolls and 1,300 technical and white-collar employees. The return of those who were on unpaid leave will boost the blue-collar ranks to nearly 4,000.

Claiming some credit for reinstatement of the workers is the former head of the Ssangyong workers union, Han Sang-kyun. He had been dismissed by the auto maker for alleged involvement in a violent 77-day strike in 2009, when workers seized and occupied much of the company’s production complex at Pyongtaek.

Ssangyong officials say the rehiring of the 455 workers was a business decision taken because finances have improved, sales and production have increased and the additional skilled manpower is needed.

The announcement follows news that Ssangyong and parent company Mahindra plan to invest up to $900 million in new-vehicle development over the next five years. Ssanyong Chairman and M&M President Pawan Goenka is quoted as saying the investment will involve three new vehicle platforms and six engines.