August 6, 1984

When 74-year-old Joan Howitt broke a hip last winter, the fear of not knowing where she would live when she left the hospital almost broke her spirit. Mary Beaman, 72, said the stillness of her rambling house, near Sackett Lake, where she has lived for 50 years, began to grate on her last January. Now the two women are living together, sharing Mrs. Beaman's house, thanks to a match made by a Sullivan County project for the elderly. Having a companion, Mrs. Beaman said, ''gave new life to the old house.'' Like Mrs. Howitt and Mrs. Beaman, a growing number of elderly people in the New York metropolitan area and nationwide are sharing homes - to save money, stave off loneliness and avoid going to a nursing home, according to social workers and other authorities on the problems of the aging.

With a daring that successfully challenged the finest female distance runners in the world and an ease that surprised even herself, Joan Benoit took a calculated risk, ran away from the field after passing the three-mile mark, and won the first Olympic marathon for women this morning. Miss Benoit finished in 2 hours 24 minutes and 52 seconds, about 430 meters ahead of Grete Waitz of Norway, the world champion who had never before lost a marathon she had finished. Their emergence from the dark tunnel into the sunlight of the Los Angeles Memorial Coliseum began a series of celebrations at the end of the 26-mile, 385-yard course, the first women's Olympic race longer than 1,500 meters. Later at the Coliseum, Edwin Moses of Laguna Hills, Calif., won the gold medal in the 400-meter hurdles, his 105th consecutive victory in the event. (Page C1).

On the basis of all they have said in the election campaign about taxes and spending, neither President Reagan nor Walter F. Mondale would significantly reduce the Government's record budget deficits, according to many of the nation's leading economic forecasters. The economists, weighing both candidates' statements against underlying trends in the economy and the political attitudes in Congress, predict that annual deficits would remain at the stubbornly high $200 billion level through the 1980's. ''Essentially, we think there would be little significant impact on the deficits, regardless of the outcome of the election,'' said M. Kathryn Eickhoff, executive vice president of Townsend- Greenspan, a New York forecasting firm. A Dominant Campaign Issue Robert Gough, senior vice president of Data Resources Inc. in Lexington, Mass., said the ''only major impact'' of Mr. Mondale's proposals ''is that you would prevent it from getting much worse.'' To most economists, the current budget deficits, triple those of any previous Administration, have become the greatest menace to the economy since the surging oil prices of the 1970's. Now the deficits, and whether to raise taxes to bring them down, have become the dominant economic issue of the Presidential campaign.

Like hundreds of portfolio managers in charge of big pools of money, Andrew Furtak of the $1.3 billion IDS Stock Fund heard the rumble of a market rally last week and sprung into action. Suddenly, caught up in a roaring, get-there-first stampede of investors, he was ordering tens of millions of dollars worth of stock in such issues as International Business Machines, General Electric, Motorola and Texas Instruments. Wall Street had never seen anything like it. Record volume on Thursday and Friday of last week led to the best weekly price advance in history. Asking the Same Question Investors everywhere were asking the same question: ''Is this 1982 all over again?'' The market took off in August 1982, setting record volume with unrelenting momentum that took the Dow Jones industrial average up about 50 percent over the ensuing five months.

LOS ANGELESFirst there were gasps, then there were cheers, and later there were questions, hard questions. The first women's Olympic marathon in history was turning into a controversy over an issue that could have been a matter of life and death. The gasps began after Joan Benoit loped into the Coliseum, easily winning the 26-mile, 385-yard race that Olympic officials had never allowed women to run before. The crowd saluted Miss Benoit, but later it gasped for Gabriela Andersen-Schiess.