General Motors Co. would pay $420 million as signing bonuses to union workers after approval of a new four-year wage agreement similar to that reached at Fiat Chrysler Automobiles NV earlier this month, according to details provided by union officials.

The No. 1 U.S. auto maker by sales also agreed to invest $1.9 billion in U.S. facilities over the life contract on top of already announced $6.4 billion in production investments this year. The new investments would create or retain more than 3,300 jobs at 12 work sites, union officials said.

General Motors also would offer a $60,000 retirement incentive to up to 4,000 eligible production employees who agreed to leave the company between Feb. 1 and May 1, 2016, according to United Auto Workers union officials.

A General Motors spokeswoman declined to comment on the deal’s terms.

UAW President Dennis Williams and Vice President Cindy Estrada briefed local union leaders on the details on Wednesday, and later outlined the agreement during a news conference. The UAW pushed for a better deal with GM because the auto maker is larger and more profitable than Fiat Chrysler, they said.