Julio Gallo, who helped to build the immense E.& J. Gallo Winery and in the process helped change Americans' drinking tastes, was killed in May 1993 when a vehicle he was driving veered off a dirt road on a family ranch near Tracy, Calif., about 80 miles east of San Francisco. He was 83. Mr. Gallo, the longtime president of the company, which is one of the world's largest winemakers, was driving the vehicle, The Modesto Bee, a California newspaper, reported yesterday. He was flown by helicopter to Memorial Medical Center in Modesto, where he was declared dead on arrival. According to the Stanislaus County coroner, he died of a cervical spine fracture and partial dislocation caused by blunt-force trauma. Family Injured Mr. Gallo's wife, Aileen, and two granddaughters were in the vehicle, a Jeep Wrangler, which plunged 35 feet down an embankment and into a shallow pond, an officer of the Tracy rural fire department said. Mrs. Gallo, who is 80, and Gina Gallo, 26, were injured in the accident and were taken to Eden Hospital in Castro Valley, where Mrs. Gallo was treated for a fractured sternum and rib and Gina Gallo for fractured ribs. Both were reported to be in satisfactory condition and were released yesterday. The other granddaughter, Amie Gallo, 22, was not hospitalized. Mr. Gallo was born March 21, 1910, in Oakland, Calif., grew up outside Modesto and was graduated in 1929 from Modesto High School. In his early years, he labored in a vineyard near Modesto that belonged to his father, an immigrant from the Piedmont region, in north and northwestern Italy, which also has a wine industry. In addition to his wife and the two granddaughters, Julio Gallo is survived by a son, Robert J. of Modesto; a daughter, Susan Coleman, and numerous other grandchildren and great-grandchildren.