On a cloudless night last August, a private, two-engine airplane traveling from New York to Acapulo crashed into a mountainside south of Mexico City. When the burned wreckage was found, all that remained of those aboard were the parts of two bodies believed to have been the plane's pilots, and a torso identified as that of David Graiver, 35, a well-known Argentine financier.

Eight months after his death, the name and face of Graiver again are on the front page of every Argentine newspaper. It seems that the bearded, puffy-eyed businessman with a premature paunch was the central figure in what has become known here as the "Argentine Watergate."

The story has all the elements of a pulp novel of international intrigue - guerrilla terrorists, clandestine activities of people in high places, kidnappings, and millions of dollars moving to and from banks in Argentina, the United States and Europe. It is the kind of story that the Argentine appetite for political scandal - nourished for decades by corruption and coups thrives on.

Aside from wild press speculation, what is known is that the government is investigating Graiver's business connections. Important people with major or minor Graiver connections are dropping like flies - some officially arrested, other unofficially "disappeared." The ruling military junta, a taciturn regime not given to public explanations, has said only that, in the words of a junta member, air force commander Orlando Agosti, "the public will know the truth shortly, and it will include some truly surprising facts."

According to several highly placed sources, the junta believes that Graiver served as a banker, investment broker and general financial front man for the Monotneros, and underground guerrilla group that for several years has beeb a terrorist scourge here.

So obsessive is the junta's hatred of the Montoneros that for a time the very word was banned from public use, bombings, kidnappings and murders - committed in the name of a social revolution whose goals are-defined - have been the justification for virtually every type of repression and human rights violation committed by the junta.

If it can be proven that Gravier - violation committed by the junta, the wonder-boy son of Polish immigrant Jews who turned his father's substantial business into a multimillion dollar international empire - was mixed up with the Montoneros, the junta believes it can also be proven that the roots of subversion extend into the very fabric of the Argentine economy. Graiver served in the government of Gen. Alejandro Lanusse in the early 1970s. He had business dealings with countless Argentines, including former government officials. All are now suspect.

Sources said the junta believes Graiver took Montonero money, put it in banks here and abroad, bought the guerrillas partnerships in banks, bought stores and industrial plants, real estate and even part of a newspaper. They allege that he paid the guerrillas monthly dividends that kept their warfare rolling.

The Montoneros apparently have had a good deal of money to invest - most of it from ransoms. For example, they admitted kidnapping Juan and Jorge Born, scions of the Bunge and Born group, a worldwide conglomerate with major Argentine holdings. The record Born ransom, paid in 1975, has been reliably estimated at between $40 million and $60 million. Three years earlier, Graiver's brother was briefly kidnaped for a smaller ransom.

Early last year, Graiver, through his father, tried to buy controlling interest in the American Bank and Trust Co. in New York, where he lived for several months before his death. He was posthumously turned down last September after the New York State banking superintendent discovered that 89 per cent of the bank's capital was tied up in loans to Graiver interests. American Bank and Trust, additionally cited in various shady deals with New York City politicians, was later sold to Israel banking interests.

Unfortunately, Graiver's death has left a huge informational void in the investigation of who knew about, or participated in his alleged subversive pursuits. Chief on the junts's list of suspects is Jose Gelbard, who was an economy minister in the Peron government ousted by the junta. Gelbard, according to one junta source, is alleged to have introduced Graiver to the Montoneros. [Gelbard, who now lives in Washington, has denied having any connection with the guerrillas.]

At that time - the early 1970s - the source pointed out, it was not only acceptable to be associated with Montoneros, it was desirable. A select segment of the Peronist party - the political movement of labor unions and workers that formed the power base of the late President Juan Peron - they later splintered on ideological grounds, went underground and joined forces with radical Marxists.

Junta sources alleged that since Graiver's death, the Montoneros have been unable to get their hands on their money. The sources say the junta believes Gelbard may know something about where the Montonero money is. The government has already asked the United States for Gelbard's extradition, on apparently unrelated charges of misuse of public funds. Even though the extradition is "now even more urgent," a government official said, no one really thinks the United States will agree.

Here the plot thickens. Gelbard is also part of what some press speculators have labelled "the Jewish connection." Argentina is, in law and spirit, a Catholic country where Jews are ousiders. Every time the Polish-born Gelbard, is mentioned in print here, his religion follows his name, like a political party designation. He is perhaps the only Jew to have served in an Argentine Cabinet. There are no Jews know to hold high position in the military. At the time of the coup a year ago, the junta decreed the lifting Gelbard's citizenship.

It is common belief here, that Jews, ostensibly because they have many children in the university radical hotbets and substantial financial holdings, formed a more than representive past of early terrorist groups.

Jacobo Timerman is also Jewish. Timerman, the publisher of La Opinion, one of Beunos Aires' leading daily newspapers, and Entique Jara, the paper's general manager, were taken from their homes early Friday by armed men who said the two were wanted for questioning on the Graiver case.

Sources at La Opinion said that Graiver was one of Timerman's largest financial backers when the newspaper was started in 1971. They said Timerman, a widely respected figure whose paper has risked the censorship wrath of the junta several times, and been closed down twice; frequently visited Graiver in New York.

At the time of their election, Timerman and Jara were told to bring warm clothing, and cigarettes since they might be away from home for some time.

Such occurrences are common these days in Argentina. What is uncommon is that the junta has released the names of Timerman, Jara and 15 [WORD ILLEGIBLE] apparently held for some time in connection with the case. They include Gariver's wife, brother and father. It is assumed that the release of names means the junta feels it is close to closing the case.

Also on the list is Gustavo Caraballo, Gelbard's lawyer who recently visited him in Washington. The reason for the detentions, without charges, is given as "an investigation of various subversive activities." "Economic delinquency," the military press release said mysteriously, "should be attacked with equal vigor as armed subversion. The health of the republic needs such examples."

Still unclear are the whereabouts of several prominent journalists whose disappearances in the past several weeks have been linked to the Graiver investigation in press accounts. One, a former priest who worked for a local news agency, was found by the side of the road last week, his body riddled with bullets.

Another, Edgardo Sajon, a member of the La Opinion board of directors, has not turned up. Sajon served as press secretary to Gen. Lanusse, who called for the 1979 return to democracy that saw Person reelected. Many in the military have never forgiven Lanusse for that.

As is customary, junta officials attribute those disappearances to the Montoneros who, it is said, felt the men knew too much about Montonero finances. Other possibilities are that they were picked up by the junta or by military ultra-rightists who had a grudge against them that many or many have not been related to the Graiver case.

In Argentine, one never knows tle is confirmed, much is speculated and people disappear daily. Sometimes they reappear, with tales of secret government torture chambers and fortresses where thousands are hidden. Others come back and say simply, with an air of mystery, that they "had to leave town for a couple of days."

One rumor could keep this story alive: in the coffee shops of Buenos Aires, they whisper that Graiver never died, that the torso cremated in a Mexican funeral parlor, was not really David Graiver after all.