General Motors Corp. has announced plans to build a midsize version of its Chevrolet Avalanche SUV/pickup under the GMC brand in an effort to lure buyers of both kinds of trucks. GM also will install a four-wheel steering system in its GMC Sierra Denali pickup this year, making it the first truck with Delphi Automotive Systems Corp.'s Quadrasteer steering designed for tighter turns, according to spokesman Rick Asher. General Motors said it will introduce the hybrid sport utility and pickup "in a couple of years." The company's first SUV/pickup hybrid, the Avalanche, went on sale in June and features a movable mid-gate that lets the rear passenger area convert to a pickup bed. A Cadillac version will go on sale this year. GM is making a major effort to attract customers as competition increases from Asia-based automakers. The company sold 3,516 Avalanches in June.