General Motors Corp. disclosed that the nearly-two-month strikes at two Flint, MI, plants reduced its second and third-quarter profits by $2.83 billion, according to its second-quarter 10-Q filing with the Securities and Exchange Commission.

While that figure is larger than most analysts' estimates, GM officials say it will make up part of that loss by operating on very heavy overtime schedules through the rest of the year. But even so, the net negative effect on 1998 earnings will be about $2 billion.

GM also revealed that its July production loss amounted to 318,000 cars and trucks, in addition to the 227,000 vehicles lost in June, bringing the total impact of the strike to 545,000 vehicles.

Of the $2.83 billion in lost profits, $2.19 billion is assessed to its North American vehicle operations and $640 million comes out of the bottom line of Delphi Automotive Systems, GM's parts-producing subsidiary that will become a separate company next year.