What was going on when I was born?

The National Highway Traffic Safety Administration said today that it had reached a preliminary finding that could lead to a recall of more than five million General Motors vehicles. The apparent defect involves the split rear axles of the mid-size A-body line of cars manufactured in model years 1978 through 1980, and could cause the wheels to separate from the axles without warning. This could produce a potential ''catastrophic event'' if the failure occurred while a vehicle was in motion, the safety agency said.

In the midst of the jungle six miles from here, a barbed-wire barrier marks the frontier between Costa Rica and Nicaragua. A concrete marker, knee-high and nearly covered by grass, notifies the visitor that this is the border. Otherwise, the barrier looks more like the work of a farmer trying to keep his cattle from wandering too far. In recent weeks, as in the past, this border has become a problem for Nicaragua. Refugees fleeing Nicaragua have been crossing it in greater numbers - over 800 in the last three weeks. At the same time, Costa Rican border patrols have found small abandoned base camps on Costa Rican territory that were said to have been organized by anti-Sandinist Nicaraguans.

President Reagan's special commission studying ways to deploy the proposed MX missile has decided to recommend basing 100 missiles in existing but newly strengthened silos, Administration officials said tonight. Whether Congress, which has already voted against deploying the MX in the present Minuteman missile silos, will agree to the recommendation is a ''tough call,'' one official said. Perhaps no military decision in recent times has been so troubled as finding a base for the MX missiles. The critical issue has been to find a base in which the missiles could survive a nuclear attack and be fired in retaliation.

The Reagan Administration has held up final approval of the sale of 75 F-16 fighter-bombers to Israel not because of any specific Israeli violation of arms agreements with the United States, but because providing the planes now would violate ''the spirit of the law,'' Administration officials said today. They added that the approval was also being delayed to prod the Israelis to reach agreement on withdrawal of their forces from Lebanon and to avoid angering friendly Arab governments. President Reagan said Thursday that approval of the shipment of the F-16's was ''forbidden by law'' because of Israel's ''occupying'' of Lebanon. Israeli officials, including Foreign Minister Yitzhak Shamir, reacted angrily today to Mr. Reagan's statement.

In an unusually strong protectionist action, President Reagan today ordered a tenfold increase in tariffs for imported heavyweight motorycles. The impact of Mr. Reagan's action, which followed the unanimous recommendation of his trade advisers, is effectively limited to Japanese manufacturers, which dominate every sector of the American motorycycle market. The action was exceptional for protecting a single American company, the Harley-Davidson Motor Company of Milwaukee, the sole surviving American maker of motorcycles. The only comparable trade action by this Administration, the President's decision last May to impose quotas on sugar imports for the first time since 1974, was aimed at an entire industry.

Unemployment in March was virtually unchanged from the two months before, at 10.1 percent of the labor force, the Labor Department said today. But there were signs of moderate improvement in the number of people employed in manufacturing, The seasonally adjusted 10.1 percent figure, a decline of one-tenth of a percentage point from the January and February rates, included members of the armed forces. The March unemployment rate for the civilian labor force was 10.3, also a decline of one-tenth of a point from the two previous months. In New York City, however, unemployment showed a sharp rise, to 11 percent in March from 9.2 percent in February. New York State's rate also rose, but New Jersey's remained virtually stable. (Page 25.)

Foreign Minister Yitzhak Shamir said today that President Reagan had made ''a regrettable pronouncement'' in announcing that the United States would not give final approval for the sale of 75 F-16 fighter planes to Israel until it withdrew from Lebanon. He said the statement came just as Israel and Lebanon were ''close to agreement'' on an Israeli withdrawal. Interviewed on Israeli television, Mr. Shamir particularly criticized the President's statement that the planes could not be sold to Israel while its forces were ''occupying another country.'' The proposed sale called for delivery of the planes to begin in 1985 at the earliest.

A driver protested furiously on a chaotic main street this week as a Cairo traffic policeman scribbled a parking violation ticket. The driver's angry cries drew a crowd, most of whom sympathized with him. But the policeman was unmoved. The issuance of a ticket is an ordinary enough event in most places, but not here. Baksheesh is endemic at all levels of society. The word is hard to translate; it can be a tip or a bribe.

Following is a letter sent by Walter J. Stoessel Jr. on July 15, 1982, when he was Acting Secretary of State, to Senator Charles H. Percy, chairman of the Senate Foreign Relations Committee. The letter, classified when sent, was declassified on Sept. 10. Dear Mr. Chairman: I'm providing the following information pursuant to section 3 (c) (2) of the Arms Export Control Act. On June 6, Israeli forces entered Lebanon and began a series of military operations against Palestinian and Syrian forces. These operations have involved the use of a large quantity and variety of defense articles that had been furnished to Israel under the Foreign Military Sales program, including armored vehicles, aircraft and munitions of various types.

Thousands of protesters formed a human chain stretching 14 miles across the English countryside today. The chain ended two days of protests planned by Britain's largest antinuclear weapons group, the Campaign for Nuclear Disarmament. The police said the demonstrations were peaceful, although nearly 200 protesters climbed over or through a perimeter fence at the Greenham Common Air Base, about 35 miles west of London, before being stopped.

Eight Soviet Jews - writers, scholars, a military man and a cinematographer -published a statement in Pravda today that criticized ''international Zionism'' for purporting to speak on behalf of Soviet Jews. The group's statement in the Communist Party paper also proposed the establishment of an ''anti-Zionist committee of the Soviet public.'' The eight Jews, led by Col. Gen. David A. Dragunsky, said they ''resolutely protest'' the efforts by ''Zionist leaders'' to convince the world that there is any such thing as a ''Jewish question'' in the Soviet Union. A senior American diplomat here expressed concern over the formation of the committee, which he said could be the start of an effort to build a barrier between Soviet Jews and Jews in the West.

French police officials said today that they had arrested a man for of passing industrial secrets to the Soviet Union. The police said the man, Patrick Guerrier, 25 years old, an archivist for a company that officials would not identify, had photocopied documents and passed them to officials of the Soviet Embassy whom the police identified as agents of the K.G.B., the Soviet intelligence agency.