Dozens of delivery trucks have been firebombed or struck with rocks and lead pipes. One substitute driver was beaten with a baseball bat. Several newsstand dealers have been threatened by men wearing ski masks.

Still, for the first time in New York City history, a daily newspaper is being published and at least partially distributed despite a

strike by most of its unionized employees.

Whatever the outcome of the six-day strike against the Daily News, a tabloid known for its colorful columnists and clever headlines such as "FORD TO CITY: DROP DEAD," it marks a dramatic end to the era when a handful of labor leaders could shut down big-city newspapers at will.

Computer technology, more aggressive management and a large pool of replacement workers willing to cross picket lines have combined to give many publishers the upper hand.

New York's newspaper unions "are living almost in another century," said James Squires, former editor of the Chicago Tribune and now a visiting lecturer at Harvard University's John F. Kennedy School of Government. "The guys who want 14 men on a press, the guys who wanted to be paid for not driving . . . they're committing suicide."

"It's basically a rear-guard action the unions are destined to lose," said Everett Dennis, director of the Gannett Center for Media Studies at Columbia University. "I think they're destined to die eventually. They are displaced people in the world of modern technology."

The strife at the nation's second-largest metropolitan newspaper, which has lost $115 million and 700,000 in circulation over the last decade, follows more than a year of animosity between the nine striking unions and the Tribune Co., the News's corporate parent based in Chicago.

During 10 months of contract talks, management assailed alleged featherbedding among pressmen and drivers and hired a Tennessee law firm with a reputation for breaking unions. Labor leaders, in turn, accused the Tribune Co. of adopting a secret plan to close the 71-year-old tabloid and avoid $150 million in shutdown costs.

"The most likely scenario is they'll be forced to shut down and they'll blame the unions for it," said veteran labor negotiator Theodore W. Kheel, an adviser to the News unions. "It's a no-lose situation for them. If they succeed {in breaking the unions}, fine. If they go out of business, that's fine, too . . . . It's terribly depressing."

The walkout grew out of a petty dispute about a union employee who insisted on sitting down as he handled bundled papers on a conveyor belt. The News, which has been training a nonunion work force for months, rushed in with replacements.

"It's the first time I know that management has called a strike," union spokesman Richard Weiss said. "Within 15 minutes, the bus was there with the 'scabs.' How many nights did they have that bus sitting out there waiting for the right moment?"

News spokeswoman Lisa Robinson said the company had "every legal right to bring in replacements" and dismissed suggestions that it planned to close the paper. She called the violence "really horrifying," adding that unspecified threats have been made against management officials. Police have made more than 40 arrests, several dealers say they have been threatened and some bundles of papers have been stolen off streets.

An employee at the Corner 1 Stop in Brooklyn said the convenience store's windows were smashed after the strike began. "Three guys with masks came in the middle of the night and said, 'This is just a warning. Next time we'll burn down your store,' " the employee said.

Robinson said the News is

distributing about three-fourths

of the usual 1.2 million weekday

circulation, although a random check of Manhattan newsstands yesterday found none carrying the tabloid.

The unions, representing 2,200 strikers, have called for an advertiser boycott amid signs that some companies are considering withdrawing their ads.

Chances for a negotiated settlement seem remote because management says strikers have been replaced permanently. Kheel said such strategy became more commonplace after The Washington Post replaced its striking pressmen in 1975, breaking the union. The Chicago Tribune broke its pressmen's union after a 1985 strike. Drivers did not join either of those walkouts.

The News has put out sizable papers with managers working 16-hour shifts and 24 reporters and editors imported from the Chicago Tribune and from Tribune-owned papers in Fort Lauderdale, Orlando and Newport News. Only a fraction of journalists represented by the Newspaper Guild have returned to work.

Reporter Lizette Alvarez said she is "scared" because management "can win and most of us know it . . . . We know that, if some re- porters start to go back inside,

then we'll all lose because they will be able to produce a decent product."

On their own, many Guild locals have little clout. In a typical protest, reporters at the Dayton Daily News withheld their bylines last week to draw attention to a long-running contract dispute.

Sandy Polaski, former director of the Washington-Baltimore Newspaper Guild, said unions now apply pressure through work slowdowns, consumer boycotts and lawsuits. While papers can publish during a strike, she said, "Whether they can survive as a profitable company, and have a normal relationship with their community, is a different question than just getting ink on paper."

Squires said paternalistic owners have been replaced by profit-minded managements under pressure from shareholders to make their operations more efficient. The most overmanned craft unions, at the News and elsewhere, are all-white bastions in which many jobs are handed down from father to son, he said.

Craft unions called 45 to 50 strikes a year during the 1970s but rarely walk out today, according to newspaper analyst John Morton. "You have a lot of papers in middle-sized markets forcing the unions to accept two-tiered wage scales," he said. "Unions have been decertifying in smaller markets all over the country."

Staff writer Michael Specter in New York contributed to this report.