Five years after the military coup that toppled the Marxist government of the late Salvador Allende, the old economic and political divisions that have played such an important role in modern Chile are reasserting themselves.

Chileans are less inhibited about expressing their opposition to President Augusto Pinochet and the policies of the harsh, authoritarian government he has headed since Sept. 11, 1973.

The government will mark the fifth anniversary of the coup today with a number of special activities, including a mass and a speech by Gen. Pinochet. It is widely expected that he will announce several new steps toward his stated goal of returning Chile to some form of "controlled democracy" five or six years from now.

Most of the expressed opposition to his rule has been over economic matters so far. But Chileans are beginning to speak about democracy again.

The military government is still firmly in control, although there have been some recent public cracks in its veneer. It has eased restrictions on the press, but political parties and most union activity are still strictly banned.

There can be little doubt that many middle-and upper-class Chileans, fearful of a return to the political strife and economic chaos that marked the last year of Allende's government are firmly behind the current government.

But many other Chileans dramatically raise their noses and take a deep breath when asked whether they think a change is coming. Something is in the air.

"The political turbulence in Chile has started again, there is no question," a Latin American diplomat who has served here for six years said the other day. "The people are losing their fear. They speak in the cinemas. They speak in the buses. It is very impressive."

This past week, students at Santiago's two important universities held three separate demonstrations asking for the right to elect their student leaders, for more freedom on the government-controlled campuses and, most significantly, for a return to democracy.

Workers at Chile's largest copper mine, Chuquicamata, continued demanding higher wages despite the arrest of more than 50 workers and a state of siege imposed by the government to quell the labor dispute. While that protest was going full tilt last week, workers at the state-owned steel company near Conception began boy-cotting lunchrooms, the same tactic originally used by the copper workers, to demand more money.

Strikes are illegal and the government followed its usual tactic of accusing Communists, socialists and Christian Democrats of being behind the protests at Chuquicamata and the steel works. But on Friday, 31 of Chile's most important union leaders held an unusual press conference and distributed a statement which said:

"The government can say we're Communists. The government can say we're Christian Democrats. But we will continue defending the rights of the workers" no matter what the government says.

Meanwhile, Leon Vilarin, the resident of the Union of Independent Truck Drivers - whose famous mouths-long refusal to transport food to Santiago in 1973 helped bring the Allende government to its Knees - held a press conference, too.

Vilarin, whose anti-Communist credentials are well known, said the government's "Chicago school" economic policies have almost ruined the truckers. Chile, he said, is being run "by a civilian dictatorship backed by the armed forces," a reference to the free-market, capitalist economists and financiers whose economic policies and interests have been imposed by the military government since 1973.

These policies have had an enormous impact, reducing inflation from an estimated 700 to 1,000 percent at the time of the coup to about 40 percent this year. Real growth has spurted from almost nothing five years ago to 7 percent last year.Chile now has healthy international reserves and the currency is stable. A black market for dollars no longer exists.

At the same time, Santiago stores are filled with a wide array of imported consumer goods brought in under reduced tariffs - part of the government's policy of forcing Childean manufacturers either to become efficient enough to compete or go bankrupt. That has happened to many of them as they find they cannot match goods produced in Japan, the United States or Western Europe.

The social costs of the Chilean economic system have also been enormous: unemployment is still running at around 13 percent in Santiago. Another 3 percent of the workforce receives less than $30 a month under a government employment program. Food subsidies have been reduced and, overall, Chileans now have about as much real disposable income as they did when Allende was elected in 1970.

One cannot walk for even a block, day or night, in downtown Santiago without being asked for money by a beggar. Small children scurry along the sidewalks with their hands out, strangers ask for cigarettes. Crime, despite authoritarian controls, has begun to climb.

Following the economic chaos at the end of the Allende period, many Chileans were willing to put up with the sacrifices the military government asked them to make - and many welcomed the imposed order after three years of strikes and political demonstrations.

But after five years, Chileans are beginning to forget about the food shortages and lack of consumer goods at the end of the Allende years. They are beginning to remember that during the later half of the 1960s, the Christian Democrats, under the leadership of president Eduardo Frei, provided both economic progress and political order.

It may be that this is the reason that the current government has begun to denounce the Christian Democrats as vociferously as their archenemies, the Communists.

While the first stirrings of discontent are evident, the vast majority of Chileans seem to be sitting back, waiting to see if things go much further - and waiting to see how the government reacts.

So far, despite some harsh government rhetoric, such as Interior Minister Sergio Fernandez' accusations last week that the political parties encouraged labor problems in copper and steel, the government seems to be willing to let the students hold their small and peaceful demonstrations and it continues to negotiate with the workers at Chuquicamata.

Some workers there have been arrested but, in line with the general improvement in the human rights situation here and the decrease in secret police activity since the beginning of this year, there have been no reports of disappearances, or torture as there would have been a year ago.

Pinochet's ideas on "controlled democracy," which are unacceptable to Chile's traditional democrats, include radically redefining the role of political parties. They would become "currents of opinion" but would not be allowed to field in future elections. Also, the president has in mind institutionalizing the current economic policies and creating an electoral tribunal that would have the power to decide when a candidate for office was advocating ideas incompatible with a new constitution - which would proscribe communism and other leftist political and economic ideas.

Whether Pinochet will be around to see his ideas through is the topic of much debate and is one of the reasons so many Chileans are sniffing the air, sensing that the wind may be shifting.

Even Pinochet's supporters say that he has become something of a liability and may not be the man to lead the country back to civilian rule. While his oppoinents would like to see Pinochet gone from the scene tomorrow, his supporters think another two to three years are necessary.

Whenever Pinochet's departure, most politicians seem to feel it will be several years before civilian rule is restored.

But, in addition to the growing discontent withing the country, two major international problems loom: an increasingly nasty border dispute with Argentina over the Beagle Channel in the far sough that lead to war, and the U.S. request for the extradition of three former secret police officers charged with the 1976 assassination of Orlando Letelier, one of Allende's chief ministers.

Both of these problems are believed here to be extremely dangerous for Pinochet, who faces them with few friends in the world.

Pinochet has become such a symbol of past human rights abuses that it is said here that his fellow generals may decide Chile needs an improved international image to get through the crises ahead. New leadership would provide that new image while giving the military more time for the internal changes they feel must still be implemented before a return to democracy.

This may all be wishful thinking on the part of Pinochet's opponents but the rumors have been so strong that one of Chile's highest-ranking army generals, Herman Brady, recently felt it necessary to deny them in an interview. But Brady's interview did not stop the talk.

Something still seems to be in the air.