The speculation may be endless, and the production numbers may be significant, but don't count on General Motors Corp. to withdraw any time soon from the New United Motor Mfg. Inc. joint venture with Toyota Motor Corp.

Toyota linked up with GM in 1984 to convert GM's Fremont, CA, plant to the Toyota Production System, a move that rescued the plant from closing and stimulated GM to push for greater efficiency elsewhere.

Fourteen years later, the plant is a success, producing approximately 350,000 units a year since 1994. The same production target is expected to be hit in 1999.

Most of that production, however, is for Toyota Corolla subcompacts and Tacoma pickups. In 1987, the plant produced 187,000 vehicles - most of them Chevrolet Novas - and only 43,000 Corollas.

Today, those proportions are more than reversed. Corolla and Tacoma numbers have steadily climbed, while Chevrolet Prizm numbers have dropped dramatically to 38,000 units as of October - a mere 10% of plant output.

Despite the numbers, several sources have said recently that Chevrolet is not preparing to drop Prizm.

NUMMI spokesman Michael Damer says GM and Toyota "remain firmly committed to the company and its future. This company was established to see if American workers, suppliers and facilities could make products to match Toyota quality, and they have achieved that goal." GM purchasing chief Harold Kutner says that his company has learned a great deal from NUMMI, and that he does not think GM will divest its share of the venture.

Mr. Damer notes that both GM and Toyota have made significant investments in the 4,600-employee plant. NUMMI will open a new paint shop in a few months, and expansions were recently completed in the stamping plant and in the plastics plant. - Tom Murphy