El Salvador shake-up: just a finger in the dike, or a return to stability?

The reshuffling of government and military officials in El Salvador to avert a rightwing political comeback is a last-ditch effort to resolve tensions tearing at the fabric of Salvadorean society.

All three power groups in the country -- the Roman Catholic Church, the Army, and the state -- are at odds with one another.

That, and not the radical left, is the most serious immediate problem faced by any centrist government to emerge in this beleaguered Central American republic. As one diplomat puts it: "This is a place drifting toward chaos."

It took the military officers and civilian Christian Democrats in the government eight days of negotiation to reorganize the ruling junta and make Jose Napoleon Duarte the first civilian president of El Salvador in 50 years. Mr. Duarte, who has been the most powerful civilian in the government for 11 months, is a moderate who earned the trust of the Army brass after the government was reorganized in January.

At the same time, Col. Jaime Abdul Gutierrez, one of the architects of the bloodless coup that hatched the "October revolution" of 1979, was named vice-president with complete control over military operations. His mission will be to disconnect links between the security forces and illegal death squads that roam through the sweltering countryside.

This week Mr. Gutierrez announced that a plebiscite will be held in October to determine whether citizens want a general election in 1982. If they vote "yes," a constitutional assembly will be elected to lay plans for the vote. Sources say the government shake-up was forced by the current wave of right-wing terror assumed to be responsible for the deaths of three US nuns and a social worker.

The suspension of US military and economic aid following the slayings was interpreted as a signal that the nation should move toward full civilian rule. "There is a linkage between the deaths of the nuns and the illness of the system ," said one high US diplomat.

US officials are waiting to see if the government reformation includes the removal of Defense Minister Col. Jose Guillermo Garcia and his tough deputy, Col. Nicolas Carranza -- two commanders who have either been unwilling or unable to control ultraright violence and Army human-rights violations.

With Mr. Duarte as president, the government may win a measure of international respect and blame the deaths of the nuns on the failures of the old regime. But Mr. Duarte and Colonel Gutierrez, who were tinged by the inability of the old junta to fulfill all their reformist promises and rein in the right, will continue to face institutional infighting.

The Roman Catholic Church remains one of the chief bastions of opposition to the Army and government -- despite the assassination of popular Archbishop Oscar Arnulfo Romero last spring and the murders of nine other priests in the last three years.

As the traditional moral leader of the people, the Catholic Church continues to condemn official policy and give respectability to forces of radical change. Church leaders to not have full confidence in Duarte because of the close ties he has kept with the military.

In a fundamental sense, the reforming of the government's executive branch reflects disagreements between the Christian Democrats and their military partners in the leadership. "The Army must work within the revolutionary process," said Julio Alfredo Samayoa, secretary general of the Christian Democratic Party and labor minister. "If they would work within this framework, things would work well."

Security forces have interrupted the landreform program by shooting leaders of cooperatives and aiding paramilitary bands.

Military rightists, however, won a major victory last week by voting Col. Adolfo Arnoldo Majano, the most liberal officer in the government, out of the junta. His removal embittered "majanista" middle-level officers. One captain is threatening to take his men into the mountains to join the leftists.

"One of the Army's chief concerns is just to keep itself together," said a third diplomat.

Capital flight, soaring inflation, rising unemployment, negative growth rates , and suspension of US aid threatens an already weakened economy. Mr. Duarte will have his hands full with these as well as with coping with violence of the left and right.