What was going on when I was born?

Tenneco Inc., a pipeline company, and two major natural gas producers have agreed to pay $40 million in penalties for improper pricing policies before 1975, the Federal Energy Regulatory Commission announced today. The money will go to consumers. The companies were charged with having improperly diverted gas from interstate transmission, which was subject to Federal price controls, to intrastate markets, which were exempt from controls. Tenneco, without admitting or denying the allegations, agreed to pay $23 million in refunds, to be passed to the interstate customers of the Tennessee Gas Pipeline Company, a division of Tenneco.

France's automobile makers, long considered the most dynamic of the country's manufacturers and widely respected abroad for their technological skill, are in trouble. Faced with stagnant world demand and stepped-up competition from abroad, especially Japan, the privately-owned Peugeot-Citroen group and the nationalized Renault see their market shares falling and their profits melting away. Peugeot-Citroen has reported that its British subsidiary had a first-half loss equivalent to $68 million, a result sure to help bring about the ''substantial'' loss for the year that the group's chairman, Jean-Paul Parayre, recently warned shareholders to expect. String of Losses This year's red ink follows a loss of $277 million in 1981 and one of $208 million in 1980, converting the French franc at its current rate. The losses reflect in part the difficulty the group has experienced in integrating its three elements, the once independent Peugeot and Citroen car companies, which merged in 1974, and Chrsyler's old European subsidiaries, which were brought into the fold in 1978 and rechristened Talbot.

What's in a name? Well, maybe billions of dollars, according to some companies in the telephone equipment business. An intense behind-the-scenes debate is being waged over the name ''Bell,'' synonymous in some minds with power and success in the telephone game. The overall Bell System had revenues of more than $50 billion last year, including $13 billion for the Western Electric equipment subsidiary alone.

At 11:37 P.M. on Jan. 3, 1981, two Salvadoran National Guardsmen stepped into the Salon Las Americas, the restaurant at the Sheraton Hotel in San Salvador, and moved quickly toward a rear table where three men sat. One of the Guardsmen lifted a .45-caliber submachine gun with silencer and began firing while the second pulled the trigger on his 9-millimeter submachine gun. The three men at the table - two Americans working for the A.F.L.- C.I.O. and a Salvadoran union leader who headed a land redistribution program - were killed but their deaths were unresolved until last week. Today, in response to what they called the failure of El Salvador's legal authorities to prosecute the case in full, United States labor officials divulged details of the case for the first time.

The City Planning Commission has unanimously approved a proposal to build a new city jail adjacent to the lower Manhattan civic center, on the western edge of Chinatown. The city's Correction Department, under a court order to reduce overcrowding in its jails, announced last year that it planned to build a 500-bed detention center on a vacant block bounded by Centre, Baxter, Walker and White Streets. This jail would be near the Men's House of Detention - known as the Tombs - which is to reopen next spring with 426 beds. The plan also calls for the construction of a 126-bed juvenile detention center on top of the new jail.

International Lebanese Army soldiers conducted their first intensive search of downtown West Beirut, sealing off commercial and residential streets and taking scores of people into custody. Unofficial estimates put the number of those detained at more than 400. (Page A1, Column 6.) Sweden said it had trapped what it suspects is a Soviet submarine in coastal waters near a secret Swedish naval base. It said it was dropping depth charges to force the vessel to the surface. (A3:1-3.)

The first few days of the Italian ready-towear shows for spring and summer established the return to the casually elegant style that has become known as the Italian look. In today's shows, designers attempted to expand their share of the fashion turf. Fendi, whose superiority in fur design is rarely questioned, emphasized beach and play clothes when it started making ready-towear about four years ago. Now it is covering the field, from tailored styles to wear to work to thin leather dresses for night.

A proposal pending in Congress to limit uranium imports has angered two major American trading partners and, according to Administration officials, may endanger the Government's drive to lower international trade barriers. Canada, this nation's biggest trading partner, and Australia have objected to a provision in a bill pending before the House that would suspend new foreign uranium contracts after uranium imports exceeded 37.5 percent of total domestic demand. The provision emerged from a House-Senate compromise on the Nuclear Regulatory Commission authorization bill, which passed the Senate last Friday and is awaiting action by the House. The provision is designed to assist the ailing domestic uranium industry but, according to Canadian and Australian officials, it would disturb the international uranium market. American trade officials argue, moreover, that such a trade policy would undermine American efforts to combat protectionism and might invite retaliation.

The nation's Big Three auto makers reported today that the 1982 model year ended in late September with another drop in sales, closing out the worst year for auto sales since 1961. The outlook for 1983 models, many of which have just gone on sale, appeared nearly as bleak, in part because the inventory of 1982 models still in dealers' hands was close to one million, or more than an 80-day supply at current sales levels. Industry leaders, who consider a 60-day supply desirable, and analysts have said sales would not rise appreciably in the fourth quarter because of the recession, but that sales should rise early next year. ''There were really no surprises,'' David Healy, an automotive analyst with Drexel Burnham Lambert Inc., said of the model year, which ended Sept. 30. ''Sales have been down a long, long time.'' He said the state of the economy, high interest rates and competition by foreign manufacturers contributed to the poor sales, adding, ''I would say it was more the economy than imports.''

Standing on a flowering bluff above the dark Atlantic, with the wind whipping his thinning hair and billowing the fields of wild goldenrod and purple aster behind him, William P. Lewis 2d pocketed a letter of intent he had just been handed. It was the confirmation of the first part of his dream. A friend pulled a bottle and glasses from a paper bag, and Mr. Lewis and Eve Endicott, a lawyer and fund-raiser for the Nature Conservancy, drank champagne against the chill gray sky. This summer, Mr. Lewis offered to sell 150 acres of this land he loves, land considered without parallel in all New England, for a public preserve. His price was $1 million, $2 million less than its market value. Thursday was the first day in a schedule of deadlines for raising the money, and a coalition of state and private groups met it. Late in starting, difficult at a time when the Reagan Administration has for budget reasons ended programs of Federal funds for the acquisition of endangered lands, the battle to save the rare character of this island from development is now under way.

While a gathering of the financial community yesterday expressed concern that the controversial Bendix-Martin Marietta takeover battle had produced an antimerger backlash, William M. Agee, chairman of the Bendix Corporation, defended his actions and denounced the defensive activities of the Martin Marietta Corporation. ''The conventional wisdom is that Bendix and Bill Agee lost,'' Mr. Agee told an audience that seemed to share that view. ''I don't believe that's the case.'' Bendix has agreed to be acquired by the Allied Corporation.

A New Melting Pot: The City in the 80's A series of articles appearing periodically. By DENA KLEIMAN Dr. Stanley Bleich had been an intern less than a month at the municipal hospital in Elmhurst, Queens, when he examined a Korean man who had obvious indications of tuberculosis. The patient coughed frequently and had trouble breathing. A chest X-ray indicated his lungs were damaged. A troublesome symptom, however, was a series of red circles that ran up and down his chest and back. Dr. Bleich did not want to disturb the patient unnecessarily by showing his surprise at this unusual symptom. He also wanted to make certain that the circles were not an indication of another disease he had overlooked. After consulting several medical texts, none of which provided information about the circles, he decided to consult a superior.