General Motors Corp., suffered a record net loss of $567 million in the third quarter, and its $953 million operating loss apparently is the largest for any U.S. company.

The net loss amounted to $1.95 a share. In the same quarter last year, the world's biggest automaker earned $21.4 million (6 cents a share).

Sales in the quarter fell 10 percent from $13.3 billion to $12 billion.

The previous record three-month loss of $562 million was set by U.S. Steel Corp. in the fourth quarter of 1979.

The July-to-September deficit brought GM's nine-month loss -- en route to its first losing year since 1921 -- to $824 million ($2.86) compared with profits of $2.47 billion ($8.58) in the same period of 1979. Sales for the nine months fell 17 percent from $50.2 billion to $41.5 billion.

GM actually lost $953 million for the quarter and $1.53 billion for the nine months, but tax credits were taken okf $386 million for the third quarter and $703 million for the nine months. In effect, those are refunds for taxes paid in 1977. U.S. tax laws permit companies to apply losses against profits earned in three previous years and claim a credit for taxes paid in those years.

The small $5 million difference between GM's reported result to the previous loss record by U.S. Steel concealed the vastly worse operating results of GM. U.S. Steel included a one-time charge of $809 million against earnings that quarter for the expenses of plant closings, while GM had no such charges.

The size of the loss did not catch Wall Street analysts by surprise. Harvey Heinbach of Merrill Lynch, Pierce, Fenner & Smith Inc. had predicted a $2-a-share third-quarter loss back in August, for example.

GM is the first company to report third-quarter results in what will be the auto industry's most disasterous year in history. Most analysts expect the Big Three companies to lose more than $4 billion.

The third quarter is always the worst for an automaker, even in the most profitable year, because of the expense of changing plants for the next model years' cars and the summer sales lull.

In addition to that usual reason for a slow quarter, GM Chairman Thomas A. Murphy and President Elliott M. Estes said in a statement that results were hurt by the recession, the shift to lower-margin small cars, inflation and GM's inability to recover its cost increases, "the cost of price incentives" through buyer and dealer rebates and the company's heavy retooling expenses.

Citing strong performances in manufacturing, apparel and agricultural products, Gulf & Western Industries Inc. reported record earnings for the final quarter and the entire fiscal year that ended July 31.

G & W, whose subsidiaries include Paramount Pictures, Consolidated Cigar and New Jersey Zinc., said it earned $63.6 million ($1.08 a share) in the quarter, up from $60.7 million $1.02) in the same quarter of 1979. Sales were $1.32 billion, up from $1.27 billion.

Full-year earnings were $255.3 million ($4.38), up from $227.4 million or $3.69 a share, and sales were $5.338 billion, up from $4.843 billion.

Chairman Charles Bluhdorn said per-share earnings were adjusted to reflect the five-for-four stock split earlier this year.

Bludhdorn said gains were made in manufacturing, apparel and home furnishings, consumer and farm products groups. Higher prices for sugar were a help. The natural resources, building materials and automotive replacement parts divisions had poorer results.

McDonnell Douglas Corp. said yesterday its profits in the third quarter nosedived to $11.7 million from $49 million in the same period last year.

The company reported per share earnings of 30 cents on sales of $1.52 billion. That is down from $1.25 a share on sales of $1.31 billion in the comparable period in 1979.

Nine-month after-tax earnings were $98.79 million ($2.50 a share) on sales of $4.56 billion compared with $147.35 million ($3.75) a year earlier on sales of $3.95 billion.