President Jose Napoleon Duarte led El Salvador's hesitant conservative establishment toward unprecedented peace talks with the Marxist guerrilla movement this week, and despite the mistrust on both sides there is hope that the negotiations might be successful.

"They should have done this years ago," several Salvadorans said in brief, informal interviews.

A character in the editorial cartoon panel of an afternoon newspaper said, "God has remembered us."

For Duarte, who has gambled on a bold peace initiative early in his five-year term, the question was whether the country's power structure has changed enough to allow him to make meaningful concessions to the left, according to political, diplomatic and academic sources. They asked whether his elected civilian government, a novelty in El Salvador, was strong enough to make peace despite opposition or at least skepticism within the Armed Forces, the business community and the violent far right.

"The Army sees this as a publicity stunt that will go nowhere," said a military source familiar with the political views of senior Salvadoran officers.

There have been subtle changes in the Armed Forces' command structure and the attitude of the conservative business community toward Duarte's moderate policies, a variety of political analysts said. The outpouring of U.S. support for Duarte has played a critical role in encouraging the nation's conservative forces to make their peace with him at least for now, the sources said.

In the Army, a group of politically astute officers with relatively moderate views have received key positions in the past year while several hard-line officers have been shipped into diplomatic exile.

But the conservative faction in the Armed Forces, now said to be grouped around Air Force commander Col. Juan Bustillo, remains powerful. The military, the business community and the conservative political opposition are likely to resist political and economic reforms proposed by Marxist guerrilla leaders.

The death squads, which have had links to some elements of the Armed Forces, are also still active, and one of the most notorious groups announced its reaction to the peace initiative today. The Secret Anticommunist Army issued a two-page communique accusing Duarte of "high treason" and warning that he and his supporters "from now on . . . will be targets of our military action."

For the guerrillas and the exiled leftist politicians allied with them, the issue seemed to be whether Monday's planned talks could revive their fortunes by reaffirming their legitimacy. Facing a president publicly committed to social and economic change and backed fully by the money-dispensing U.S. Congress, the left has fallen on the defensive both politically and militarily this year. The guerrillas have had only one dramatic success in 1984, the brief seizure of the Cerron Grande dam in June, and U.S.-supplied helicopters, ammunition and economic aid are pouring in at record levels.

As a result, the government side stands to lose little except the dream of a negotiated settlement if the peace talks fail. In that case Duarte could blame the left for being intransigent and return to the cautious style of government that he adopted from his June 1 inauguration to his surprise offer before the United Nations last Monday to meet rebel leaders, carrying no weapons, in the small pottery-making center of La Palma, 42 miles north of the capital.

"Nobody can say that Duarte had to take this action because Duarte was losing the war," a close adviser to the president said. "Ideally some committees would be formed after Monday for further meetings. But it's like Reagan seeing Gromyko: If they don't agree on the missiles, at least it's better that they began to talk."

The rebels' defensive posture was evident this week in the confusing, roller-coaster ride of proposals and counterproposals over procedural issues for the talks.

Duarte imposed on the left the place, time and intermediaries. He rejected a mediation attempt by Colombian President Belisario Betancur, who conveyed a list of proposals from the left including requests that the Salvadoran flag be flown throughout the meeting and that a minute of silence be observed for the more than 40,000 Salvadorans killed in roughly five years of civil war.

A statement from Duarte's office said that Betancur "was informed" that the Salvadoran Roman Catholic Church would serve as intermediary as it did in negotiations over a recent prisoner exchange. Duarte also rejected the left's proposal that former Venezuelan president Luis Herrera Campins and former West German chancellor Willy Brandt serve as neutral witnesses in the talks, saying that he wanted to keep the talks among Salvadorans.

Duarte's brusque approach -- partly aimed at reassuring domestic rightist critics that he was not a pushover -- drew a scathing comment yesterday evening from the mysterious man believed to be the "first among equals" in the guerrillas' military leadership.

"It is absurd that Duarte speaks of nationalizing the conflict when it is precisely he who has internationalized it," Joaquin Villalobos, commander of the Revolutionary Army of the People, said in a rare interview on the guerrillas' clandestine Radio Venceremos. Villalobos' group is one of five guerrilla armies making up the Farabundo Marti National Liberation Front.

He noted that Duarte has traveled to the United States, Western Europe and Latin America to seek political and military backing, that Duarte has welcomed sharp increases in U.S. support and that Duarte delivered his proposal at the most international forum of all, the U.N. General Assembly.

Shunning publicity as they usually do, the guerrilla leaders had not announced by this morning who would be the two military commanders to be sent to the talks. Villalobos and Ferman Cienfuegos, leader of one of the other guerrilla forces, were the only two to be interviewed on Radio Venceremos this week.

The other two leftist representatives were to be exiled politicians Guillermo Ungo and Ruben Zamora. They are the best known spokesmen for the left because they are available to provide comments to journalists, while the military commanders are thought to live in the rebel-controlled mountains near the northern border with Honduras.

The bargaining over arrangements seemed to be particularly galling for these two civilian leaders, who apparently had no way to get to El Salvador for the talks except by flying here early Monday and accepting Duarte's guarantee of safe passage to La Palma.

"Duarte has not made it easy," Ungo said last night in a telephone interview from his home in Panama.

The Salvadoran guerrilla leaders appear to be firmly committed to revolutionary Marxism. Years of living under attack in "liberated" areas and the experience of brutal repression including Army massacres and death-squad killings, have nurtured this radicalism.

For this reason, many analysts doubted that Duarte would be able to persuade the left to give up its battle in order to participate in elections.

"Nobody expects Joaquin Villalobos to come down from the hills and run for the Legislative Assembly," a U.S. official said.

Despite Duarte's good intentions, the skeptical view was that the peace bid's principal political effect could be to drive a wedge into the guerrilla movement between those willing to compromise with the government and those determined to fight on indefinitely. This has been the consistent aim of U.S. policy regarding peace talks.

The Army and the influential business community have made clear to Duarte that he will run great risks if he offers a share of power to the left in making decisions on such issues as land reform or punishment of Army officers guilty of past crimes. He is not considered likely to go much beyond past offers such as guaranteeing the security of left-wing candidates if they run in elections.

As the church, farm and labor unions enthusiastically endorsed Duarte's bid this week, optimists said his gesture might generate a momentum of its own and spawn a peace movement. That could encourage both sides to negotiate seriously but also could provoke renewed repression from the far right.

A Salvadoran political scientist, who had despaired of ever seeing negotiations, said that the country was showing signs of "peace fever."

"I think if anybody thought of this as a maneuver, then it's gotten out of hand," he said.

Certainly Duarte was trying to encourage theatrics. Thousands of Salvadorans were expected to crowd into La Palma Monday after he publicly invited the entire country to attend.

"All the Salvadoran people can [come] carrying a white flag as a demonstration of their fervent democratic commitment and their unvarying struggle in search of a road toward peace," a statement by Duarte's office said.