General Motors Corp. is resuming some previously curtailed operations at a handful of North American assembly plants, but output at 30 other facilities remains impacted by a parts shortage resulting from the strike at supplier American Axle Mfg. & Holdings Inc.

Through April, the AAM strike has cost production of 230,000 vehicles, the auto maker says.

Monday, GM resumed a third shift at its Oshawa, ON, Canada, car plant that makes the Chevrolet Impala and Buick LaCrosse and restarted the second shift on the Oshawa fullsize pickup line.

Full production also got under way at the Ramos Arizpe, Mexico, facility, home of the Chevrolet HHR. The first shift was resumed at the Wentzville, MO, fullsize van plant and the Wentzville stamping operations.

GM says there are tentative plans to call back the second shift at the Wentzville assembly plant next week.

Among assembly plants still running at reduced rates because of the strike are Arlington, TX (fullsize SUVs); Shreveport, LA (midsize pickups and Hummer H3); Toluca, Mexico (fullsize pickups and medium-duty commercial vehicles); and Janesville, WI (fullsize SUVs).

Down completely are plants in Moraine, OH (midsize SUVs) and Flint and Pontiac, MI (fullsize pickups).

The strike is forcing partial or complete shutdowns at 22 other engine, transmission, stamping and components plants.

The affected facilities employ 33,503 hourly and 4,468 salaried workers, but GM is not disclosing the specific number of layoffs resulting from the downtime.