Turmoil between left and right in Central America is nothing new. Its latest manifestation has been the murderous violence in El Salvador, where right-wing assassination squads and leftist guerrillas have been simultaneously undermining the shaky centrist government fo military men and civilians.

The next Central American hot spot, according to my intelligence and diplomatic sources, will be Guatemala. It will be a test of the Reagan administration's new "pragmatic" policy in the region, which is designed to rescue the United States from the difficulties brought on by Jimmy Carter's emphasis on human rights.

Carter cut off all aid to the right-wing rulers of El Salvador and Guatemala. When the centrist junta replaced the rightists in El Salvador a year and a half ago, he resumed economic aid. Then, after much soul-searching, he resumed military aid to the junta early this year, despite public outcry over the slaying of four American women and two U.S. labor officials.

The cutoff of aid to Guatemala has not been recinded. But my sources say that President Reagan has decided that the Guatemalan military regime, however deplorable its record on human rights, should get U.S. help to prevent a take-over by leftist elements. It's a decision the administration should consider carefully.

Little information has been coming in on the potential Guatemalan tinderbox. But the violent confrontation between right and left is only slightly less serious there. There are four active left-wing guerilla groups operating in Guatemala. They have been involved in the assassinations of important government officials and members of the right-wing business community that supports the ruling party.

Sources told my associate Bob Shedrman that the leftist rebel groups do not now enjoy widespread support among the Guatemalan people. But increased violence from the right, directed at labor leaders, university professors and workers, has not only radicalized the leftist elements but gained them sympathy among the general population.

Right-wing Guatemalan leaders elated by the election of Reagan, have openly boasted of their "close ties" to the new administration. And two rightist businessmen spent inauguration week mingling with the stars of the Reagan inner circle.

One was Mario Sandoval Alarcon, who heads Guatemala's ultra-right National Liberation Movement. Sandoval has his eye on the Guatemalan presidency in 1982. The other was Carlos Arana Osorio, a former Guatemalan president who is regarded as the real power in the current regime. Sandoval and Osorio are perceived as bitter enemies in Guatemala. But Allen Nairn, an investigator for the Council on Hemispheric Affairs, overheard them in a Washington hotel as they cordially discussed what they both considered to be good news for their mutual intersts: Reagan's take-over of the White House.

On Inauguration Day, Sandoval announced that he had met with Reagan defense and foreign policy advisers before the election, and indicated that the Guatemalan rightist expect Reagan will honor "verbal agreements" to resume military aid to Guatemala and put an end to criticism of the regime's human rights record.

Whether any such agreements were actually made is almost beside the point. The perception that they were could put the Reagan administration in an embarrassing position. It could lead the people of Latin America -- and the world -- to believe that the United States is reverting once more to the old days when Uncle Sam gave unquestioning support to military dictators in the name of anti-communism and protection of American business interests.

And lest there be any doubt about the kind of people the Reagan administration is thinking of doing business with, let me quote a radio broadcast last year by an officaial spokesman of Mario Sandoval Alarcon's National Liberation Movement: "I admit," he said, "that the MLN is the party of organized violence. Organized violence is vigor, just as organized color is scenery and organized sound is harmony. There is nothing wrong with organized violence; it is vigor, and the MLN is a vigorous movement."