General Motors will close its Saginaw Malleable Iron Plant by September 2007 and will try to help its 350 hourly and salaried employees find work elsewhere by then.

Darla Park, a spokeswoman for the automaker’s Powertrain Division, told the Associated Press the plant produces gears for automatic transmissions and production will be transferred over time to a GM foundry in Defiance, Ohio.

The Malleable Iron plant, which opened in 1917, has slightly more than 300 hourly employees and nearly 50 salaried employees, Park said. Production will end before the national contract between GM and the United Auto Workers union expires, she said.

“The market for malleable iron has reduced dramatically as more efficient materials and processes are introduced,” Rick Sutton, manager of the Malleable Iron and Saginaw Metal Castings Operations plants, said in a prepared statement cited by the Associated Press.