General Motors Corp. and its Japanese counterpart have chosen a closed Fremont, Calif., auto plant as the site of any joint car production venture, the head of the No. 1 U.S. automaker says.

Smith described GM's still not finalized car production venture with Toyota as a way to "get over the hump" until GM can improve its technology and churn out its own "quality" small cars "at the right price."

He said negotiations are continuing and a pact is expected before the end of the year. GM and Toyota had been looking at both the Fremont plant near San Jose and a second California plant in Southgate.

Both plants were closed by GM earlier this year, idling some 10,000 autoworkers.

General Motors Corp. was also reported by an industry trade journal Monday to have planned to discontinue production of its Pontiac Phoenix and Oldsmobile Omega at the end of the 1984 model year.

Wards Automotive Reports said GM's Buick division also plans to drop its X-body car, the Skylark, at the end of the 1985 modelyear.

All the cars are X-body models, GM's first front wheel drive models, and were introduced as 1980 models.