Echoes of policies past resounded in the State Department yesterday as two former secretaries of state and former president Gerald R. Ford took varying but familiar positions before the special commission on Central America set up by President Reagan to recommend long-range policy for the United States in the region.

At the same time, Special Ambassador Richard B. Stone said he hoped leftist rebels in El Salvador did not mean to reject the democratic process in their recent statements because "that would be unacceptable." He said he thought his talks with them Tuesday had been "a positive step."

Alexander M. Haig Jr., on emerging from talks with the 12-member commission headed by former secretary of state Henry A. Kissinger, said that the United States is "faced with a problem of international credibility" in Central America. Haig said policies "must involve careful integration and orchestration and linkage, if you will, with geopolitical realities."

He recalled, in vintage Haigese, that after the Cuban missile crisis "we were anguishing many of the same problems we're anguishing today."

Haig indicated that he continues to back the views of President Reagan, whom he served for 17 months as secretary of state until resigning in June of last year.

"Our problem in Central America is first and foremost global, second regional, with focus on the Cuban problem, and third in-country," Haig said. "If we fail to deal with these problems today in El Salvador, we may find them developing in areas which are less ambiguous and far more dangerous."

Former secretary of state Cyrus R. Vance, who served under Jimmy Carter, said he told the commission in his two hours of testimony that the major U.S. effort should be "behind trying to find a serious political solution" and that the Reagan administration is "not sufficiently accenting" that approach.

Vance challenged Reagan's assertion that the Soviet Union and Cuba are fostering unrest in the region. It is necessary, Vance said, to ask whether Central America's problems "are the result of local factors or whether they have their roots in Moscow or Havana. I said it was my judgment that the problems are essentially local, that they are economic, political and social, and that they must be addressed in their own terms and in their own local context."

Vance said U.S. vital interests in the area are fourfold: open access to the Panama Canal, free use of shipping lanes, assurance that no nuclear weapons are introduced and friendly relations with Mexico.

These views tally with Vance's past practice of stressing Central America's history of poverty, repression and instability over outside intervention as the prime background of regional conflicts.

Former president Ford took a middle course, saying that the conflict's roots were "a combination of both" historic and external factors.

"It's a multi-headed problem and we'd better have a broad-based program to meet the challenge," he said.

Ford said he had told the commission that it has "a tremendous obligation to come up with a program of economic and military assistance" that will win both administration and congressional support.

Summing up the testimony, Kissinger noted that the views of the three "were not unanimous" except on the point that "we cannot really afford to be divided on an issue that close to our borders." He said he was "increasingly optimistic" that the panel would achieve a consensus.

Meanwhile, Ambassador Stone left Costa Rica for El Salvador yesterday after substantive talks with Salvadoran rebels, calling the discussions "a positive step" toward peace.

But Stone expressed concern over remarks by Ruben Zamora, one of four representatives in the talks from the FMLN/FDR, the joint command of the Farabundo Marti National Liberation Front (FMLN) and the Democratic Revolutionary Front (FDR). Zamora had said that elections can be held in El Salvador only under a new government that could guarantee the leftists' safety.

"I can tell you flatly we are not going to participate in elections as planned for next year, because if we did under the present government and conditions, hundreds of us would be killed by death squads," Zamora said at a Tuesday news conference in Costa Rica.

Emerging from four hours of meetings with Salvadoran officials, Stone said Zamora's remarks "seem apparently to reject their participation in the democratic process. If the FMLN/FDR intended to communicate the impression . . . that they will either be granted power or that they will seize it, I would expect that would be unacceptable not only to the Salvadoran people but to all the people of the world.

"I hope that they don't want to say that," Stone continued. State Department officials said no further talks are scheduled.

The Kissinger commission is to meet today with Carter, former secretaries of state Dean Rusk and William P. Rogers and former special negotiator and Latin American specialist Sol Linowitz.