Six mornings a week, as the night sky gives way to day, Maria and Fernando Torres leave their small one-bedroom apartment and follow the often-deteriorating roads of Juarez to a [WORD ILLEGIBLE] industrial park. By 6:30 they are on the job - such as a technician and he as a production supervisor in an electronic factory.

Nearby and a few hours later, hundreds of other factory workers, most of them young Mexican women wearing blue smocks, break for lunch and crowd around the streetside taco, burrito and empanada vendors hustling their foods. On the left front of the smocks is a familiar embroidered patch reading, in silver on red, RCA.

Not too many years ago, the Torres' jobs, those of 1,828 coworkers and the 5.255 jobs at RCA's factory were held or would have been held by Americans working in factories scattered across the United States. Instead, today they are part of the estimated 110,000 jobs no longer held by Americans but by Mexicans in American-owned companies seeking to lower their production costs by using the cheaper labor available in a foreign country.

Those jobs have been made possible by two U.S. tariff provisions and an aggressive Mexican effort to woo labor-intensive work to this chronically job-short country.

But at a time of increasing layoffs by industries challenged by foreign competition and with a new surge of interest in foreign operations by American firms, these tariff measures have come under increasing attack by organized labor. Labor claims U.S. firms are needlessly exporting jobs to other nations paying lower wages - at the expense of the American workers - when federal policy should protect those workers.

General Motors, for example, is expected to formally announce soon a 600-to-800-employee wiring assembly plant now under construction at the same industrial park where Maria and Fernando Torres Tawes work. And the Zenith Co. last month said it will lay off 5,000 $6-an-hour U.S. workers - almost one-fourth of its work force - and transfer much of that work to $1-an-hour jobs in Mexico to reduce costs and remain competitive with the manufacturers of of imported television sets.

Zenith and others who support the use of foreign labor in the American manufacturing process, argue that the lost jobs are far outwighted by the jobs saved for Americans who continue to supply the components for the foreign operations and who often still do the final assembly work of consumer goods.

"We're saving 1,500 jobs in finals assembly, sales, marketing and other staff," said a Zenith spokesman.

Supporters of the tariff provisions argue that the alternative is the complete shutdown of American facilities in favor of cheaper operations overseas using low-cost foreign components bought on the world market. That argument, however, is disputed by organized labor, "General Motors has to send jobs to Juarez to stay in business?" asks an AFL-CIO spokesman. "That's a little hard to believe, isn't it now?"

Thus, with more than a score of bills pending in Congress to undo the provisions, the debate sharpens over whether they save jobs or eliminate them. Turning on the debate are the interests of many American businesses, hundreds of thousands of American and foreign workers, and American consumers.

Whatever the debate in the United States, there is little doubt that such developing countries as Mexico have benefited.

Meantime, the Mexican government hopes that U.S. corporations will transfer 175,000 more jobs to Mexico in the next five years. But even if that goal is achieved, it would likely have little impact on Mexico's towering unemployment or the flow of illegal aliens entering the United States in search of better jobs.

Essentially, the two tariff provisions allow U.S. companies to send goods to foreign country for processing or assembling and to reimport the assembled items at a reduced duty. In effect, the duty is calculated not on the entire value of the product, but on the value added to it outside the country.

Until the late 1960s, however, Mexican trade restrictions kept U.S. companies from taking advantage of the U.S. trade provisions in Mexico. Then, faced with thousands of unemployed workers crowded into its border cities, Mexico, on the advice of a U.S. consulting firm, relaxed its trade rules. The rush was on.

Within six years, almost 100,000 Mexicans - drawn from a labor force in which unemployment or underemployment touches one of every three workers - were employed in jobs once held by American workers.

One of the Mexican was Maria Torres, now 23, who has worked 44 hours a week at the Centralab electronic assembly plant here for six years. A former bookstore clerk who says she "had nothing to see in the future" in the way of promotions, Torres began as a machine operator and eventually was promoted to technician, maintaining and adjusting the machines.

She makes $275 a month, more than double what she would make in, say, an office job. Her husband, 31, trained as an auto mechanic, makes $550 a month - also probably twice what he would make working on cars.

"It would be a very hard situation" without the jobs, Mrs. Torres said, adding that the couple enjoys a higher standard of living as a result.

The plant assembles conductors, resistors and switches for use in radios, televisions, citizens' band radios, smoke detectors. "The Japanese were beating our brains out," Ray Dunwell, general manager of Centralab, a wholly owned subsidiary of Globe Union, said of the firm's move to Juarez in 1971. THe Juarez plant replaced assemble operations in Milwaukee, Los Angeles and Lafayette, Ind., he said, but some 1,900 U.S. workers hold jobs producing the components sent to Juarez for sub-assembly.

The general world recession of 1974 and 1974 and sharp increases in the Mexican minimum wage for the American plants combined to bring sharp cutbacks in these manufacturing operations. Now, however, an improving economy and the devaluation of the peso in 1976 have brought hiring increases that have more than overcome the job losses.

Bill Mitchell, marketing manager of the A. J. Bermudez Industrial Park here, said the park's companies, numbering about 25, should employ 16,000 people by year's end - up from the 12,000 working here in December, 1976. Burmedez, where Centralab and RCA have facilities, is the biggest industrial park in Mexico. Along the newly developed streets lined with young trees stand the factories of U.S.-owned companies - Ampex, AMF, Sylvania and General Instruments. Elsewhere in Mexico there are plants belonging to such major American corporations as General Electric and Westinghouse.

Other locations in Juarez, a city of some 700,000 people that shares the border with El Paso, Tex., provide Mexicans with 300,000 jogs in U.S.-owned firms taking advantage of tariff provisions. The city has the single biggest concentration of such jobs in Mexico.

While other countries often supply lower-cost labor for U.S. manufacturing operations, Mexico accounts for the biggest share of labor performed on goods shipped back to the United States from developing countries - $535.6 million worth in 1976 lone, about $70 million than in 1975.

But so great, is the Mexican employment problem - its population, now 62.3 million, doubless every 19 years - even these jobs from the United States have failed to ease the crush of millions of illegal aliens who have sought a better life in the United States.

Richard L.Bolin, the consultant who argued the Mexican government 10 years ago to take advantage of the U.S. trade provisions, says, the overall impact has been beneficial for the United States, despite the job losses and the objections of labor.

More than 50,000 jobs in the United States provde goods for use overseas, says Bolin, now director of the Flagstaff Institute, an Arizona-based non-profit organization seeking to increase world trade. He cited the $600 million in components sent to Mexico last year and said, "We preserve the jobs at U.S. companies. Otherwise the whole thing will go overseas."

But the AFL-CIO spokesman charges that those jobs are only temporarily salvaged and that in the end are lost as American products become less competitive due to cheaper imports.

"In the long run it flops," said the spokesman, "because what they're doing is overproducing for a market they're destroying" as workers are laid off.