General Motors is putting truck production into low gear, but industry-watchers say it could go lower still. GM plans to cut 300,000 fuel-thirsty pickups and SUVs from its production schedule by the end of 2009.

The automaker says half of the reduction will come from speeding up previously announced closures at four assembly plants. They're hinting the other half could come from canceling shifts at other factories. But analysts say it's possible another assembly plant could be shuttered, and some factories that make truck parts almost certainly will be closed.