(Reuters) - General Motors Corp announced on Tuesday a series of steps it was taking to improve its financial position and respond to higher gasoline prices the automaker now sees as a permanent threat to its business.

Chief Executive Rick Wagoner, speaking after a revised restructuring plan was approved by the automaker's board, said GM would take the following steps:

** To review Hummer brand for complete revamp of the product lineup or possible partial or complete sale.

** To reduce truck capacity by over 700,000 units. To reduce total North American capacity to 3.7 million units by 2010.

** To close four plants that build pickups, SUVs and

medium-duty trucks.

--Oshawa, Ontario truck assembly, which builds the Chevy Silverado and GMC Sierra, to close in 2009

-- Plant in Moraine, Ohio, which builds the Chevy TrailBlazer, GMC Envoy and Saab 9-7x, to close in 2010

--Janesville, Wisconsin to cease production of medium-duty trucks by the end of 2009 and of the Tahoe, Suburban and Yukon in 2010.