The rivalry and tension that have long existed among Argentina's three armed services spilled into the open over the weekend when the ruling military junta suspended two newspapers for reporting that the Army planned to reappoint Gen. Jorge Videla unilaterally as president.

While it does appear that Videla - with the strong backing of the army - will be selected at a formal meeting of the junta scheduled for Thursday, the government said it was "reckless" for the two newspapers to suggest that the navy and the air force would have no say in the matter.

In theory, all decisions must be unanimous, so the navy or air force could veto Videla's bid to remain as president. Adm. Emilio Massera, commander of the navy, has said privately that he would use his veto power, apparently hoping that some army generals who do not like Videla would look for another presidential candidate acceptable to the navy.

The generals, however, met last Friday - even as the two newspapers wert being closed - and voted overwhelmingly to give Videla their support. Massera huddled with his admirals and, late on Friday, sources within the navy acknowledged that army generals who do not like Videla future was probably over.

The succession question arises because military regulations - obeyed here even when the constitution is not - dictate the retirement shortly of the three present service commanders who comprise the junta. The navy has contended that as Videla retires as commander of the army, a new "fourth man" should be named as president.

Even the navy agrees that the president must come from the army because of its overwhelming power.

The navy could still veto Videla's bid for president, the sources said, but if the army refused to come up with another candidate, there would be a serious crisis that the navy could not abide.

Many people here believe a public split would hasten the day when the armed forces had no choice but to return the country to civilian rule.

While the army, navy and air force sometimes seem to agree on very little, they do appear to be unanimous in their hatred of Argentina's traditional politicians, especially the Peronists, that they overthrew in 1976.

The military, which has been in and out of power here since the 1930s, also seems unified in its conviction that the terrorism that plagued the country two years ago must be entirely wiped out, that the economy must be straightened out and that a political system must be created to avoid what is described as the excesses of the old politics.

The infighting within the military government is due largely to long-standing jealousies among the three services and to Massera's political ambitions for a time when the country is returned to civilian rule.

If Videla were not selected to continue as president, his replacement probably would be a "hard-line" general who would not attempt - as the military antiterrorist squads that kidnap, torture and kill suspected subversives.

Like Argentina's other military leaders, Videla is not against the use of such methods, but he is said to make a dstinction between actual terrorists and people who simply hold leftist views - a distinction that some generals do not make.

Videla is also a strong suporter of current economic polities, which are designed to hold wages down and increase imports as a means of fighting inflation.

The navy has argued that Argentine workers and industries are being strangled by these policies and that if Videla were not selected to remain as president, his replacement might be tempted to return to the more populist economic policies of the Peron era.

Videla is expected to serve as the link between the current junta, which will retire probably by Oct. 1, and the new junta of service commanders, which is to remain in power for three years more.

To achieve this aim, the military must appear united even if it is not. That was the principal reason for closing down the two newspapers, Cronica and La Opinion, because they touched the rawest nerve among the military - the junta's ability to remain united.

Although both papers will be allowed to start publication again Tuesday, the junta has by its swift action attempted to warn other newspapers and the country's 25 million people that the three services are united when it comes to their own resolve to remain in power.