In the aftermath of the bloody upheaval that left thousands dead in Aden and nearby provinces last month, there has been virtually no discernible change in the ideological direction of the ruling Marxist Yemeni Socialist Party.

Nearly six weeks after then-president Ali Nasser Mohammed's bodyguards sprayed a meeting of the Politburo with machine gun fire, setting off a near-civil war, the violence appears on the surface to have represented little more than another of the periodic reshuffles of power that have characterized South Yemen's government for much of the country's 18 years of independence.

The new president, former prime minister Haidar Abu Bakr Attas, has adopted, at least in public pronouncements, essentially the same domestic and foreign policies as his predecessor. It was Nasser Mohammed's ideological drift toward the right that ostensibly was the basis of the intraparty criticism that drove him to try to eliminate his political rivals in the bloody attack on Jan. 13.

But while South Yemen seems to have come out of the crisis still firmly allied with the Soviet Union, one result of the fighting appears to be a markedly lower Soviet profile in the only Marxist country in the Arab world.

The Soviet Embassy is in a state of semiruin, having been the target of Yemeni Army tank fire during the early stages of the fighting. A banner hung beside the Russian diplomatic enclave read, "Stop shooting Soviet citizens!" Witnesses to the first days of fighting said that an Army tank fired several salvos at the embassy and then quickly withdrew, although no explanation was offered for the attack.

Moscow has withdrawn more than 6,000 of its advisers from South Yemen.The port of Aden is devoid of Soviet troopships, and the airport shows no sign of a Soviet presence. Warsaw Pact sources said that only 600 Soviet experts remain at a radio monitoring base on the island of Socotra, about 400 miles from the capital.

Western diplomatic sources here said that the Soviets had deliberately kept a low profile during the fighting, restricting their involvement to offers of mediating a cease-fire at the height of the fighting. South Yemeni government sources said that the Soviet offer was turned down on the third day of fighting because the balance of power had clearly shifted to the anti-Nasser Mohammed forces.

Since the fighting ended, Attas and the half dozen leading party figures, who have dominated political life in South Yemen since the end of British colonial rule in 1967, have echoed a policy line calling for better relations with such conservative Arab states as Saudi Arabia and Oman, calling into question assessments by western analysts at the start of the fighting that the struggle was one between hard-line Marxists and advocates of a softer ideological stance.

While it would be simplistic to say that nothing more than personality conflicts was involved, it is clear now that deep personal rivalries and long-simmering resentment over Nasser Mohammed's attempts to concentrate power into his own hands were the dominant forces that triggered the upheaval and fueled it for such a sustained period. In retrospect, it appears that both sides exploited tribal rivalries in an attempt to tip the balance only after it became clear in the first days of fighting that a prolonged stalemate was likely.

Tribalism and personal rivalries have played a major role in recurrent political intrigue here, often centering on such issues as centralism versus local autonomy and doctrinaire socialism as opposed to pragmatism.

Following independence in 1967, six provinces were drawn by the newly established government in order to erase tribal boundaries and soften tribal allegiance. The key figures in the recent fighting represented those regions -- Nasser Mohammed of the Dathina tribe, vice president Ali Ahmed Nasser Antar of the Aden-based tribes and Attas from the highly independent tribes of the region of Hadramout, whose harsh environment suggests the meaning of its name: "death is present." Antar was killed in the conference room shooting. Nasser Mohammed was reported in Damascus, Syria, recently.

That a violent power struggle erupted within the government came as a surprise to almost no one, according to party leaders and foreign diplomats, who described the ruling 11-member Politburo as a pressure cooker of contention between Nasser Mohammed and his four chief supporters and the six-man opposition faction.

While a harsh blow by Nasser Mohammed against his critics -- or even a coup d'etat by the other side -- was widely anticipated in Aden in the weeks leading up to Jan. 13, nobody expected the degree of violence that accompanied the struggle, which included the use of tanks, gunboats and warplanes in full-scale battle.

Ali Saleh Baid, who survived the conference room machine-gunning and who was later wounded in street fighting, said that he came to the meeting armed with a revolver, indicating that a potentially violent confrontation was not completely unanticipated. But he said he was genuinely stunned at the level of violence that resulted.

"We were not expecting such a thing because the values of our party do not allow such bloodthirsty fascism to take place. It didn't come to our minds that such a thing could happen," Baid said. He said his shock increased as reports came in of massacres of hundreds of party members opposed to Nasser Mohammed.

Nobody knows how many people died in the 12 days of bitter fighting, partly because bodies are not being exhumed from dozens of mass graves that were dug at the sites of massacres and on the spot during raging street battles. Government officials said that thousands of people have been reported missing but that it is impossible to determine how many of them were killed and how many fled.

A Yemeni official said, "The truth will not come out until we are prepared to accept it."