Fifty-eight thousand, four hundred and eighty-seven dollars. That was the average income in 1976 of a man who graduated 10 years earlier from Harvard with a masters degree in business administration and a major in international business after obtaining an undergraduate degree in liberals arts or engineering.

He now works in New York City or its vicinity in an administrative capacity for a real estate or management consulting firm with fewer than 100 employees. He supervises 10 or more professionals or 50 non-specialists.

This composite picture of the most successful type of MBA - as measured by salary, commissions, bonuses and profit sharing - was drawn for MBA magazine by Abbott, Langer and Associates, a personnel management/industrial psychology consulting firm in Illinois. Abbott, Langer interviewed nearly 8,000 MBAs and devised income tables for 1965, 1970 and 1975 graduates of 25 schools. They added about 7 per cent to get 1977 income levels.

Harvard MBAs 10 years out earned on the average 25 per cent more than alumni of the next highest institution, Northwestern University. They earned more than half again as much as all the MBAs reporting, and two-thirds more than Stanford grads.

Harvard's average has been pushed up by some very highly paid alumni. Take Ghaith R. Pharaon, 37, the Saudi Arabian financier who recently bought up part of Bert Lance's shares in the National Bank of Georgia and who has other large banking and real estate interests in the U.S. He received his undergraduate degree from Stanford and his MBA from Harvard in 1965.

Dean Lawrence E. Fouraker, who taught Pharaoan, called him very intelligent, hardworking and immensely driven. His Saudi Research and Development Corp. now has assets of more than $150 million. Of course, the patronage of the Saudi royal family and vast amounts of petrodollars were also factors.

In the case of Jack Valenti, 56, it was White House influence that propelled him in 1966 from a position as a $30,000-a-year assistant to the $150,000-a-year job as head of the Motion Picture Association of America, the organization that rates films from G to X. "I don't know what kind of person I would have become if I had not graduated from there," he said. He called his 1948 Harvard MBA "the supreme credential" that enabled him to set up his own advertising agency in Houston that in turn led to his introduction to Lyndon Johnson.

A New York executive search firm, MBA Resources, offers a simple rule of thumb for the salary of managerial personnel it places: An individual with at least three years experience in the corporate world who graduated in the top third of the class should expect to exceed his or her age in thousands of dollars. Compare this with incomes reported in the magazine survey:

The median income of a Harvard MBA 10 years later was $42,250, or 28 per cent more than for the Stanford B-grad, who earned $32,925. Both were presumably in their late 30s at the time. For all MBAs surveyed, it was $31.972. When the grads of the two top schools had been in business only one year, the Harvard alumnus earned 23 per cent more; after five years, the gap narrowed to 20 per cent.

In other words, so far as the rivals are concerned, the earning power of Stanford MBAs started out about one-fourth below that of their Harvard counterparts and remained that way throughout the first decade. (This gap undoubtedly would be narrowed somewhat were the survey conducted today because both institutions reported that the median starting salary of their 1977 graduates was $22,000.)

Alumni of both B-schools increased their incomes much faster in the first five years (Harvard, 53 per cent; Stanford, 57 per cent) than did MBAs in general (41 per cent). But then the differences leveled off, with the Harvard grad making slightly bigger gains in the next five years (28 per cent) than either the Stanford alumnus (20 per cent) or all MBAs surveyed (23 per cent).

It is generally agreed that the differential results not from educational superiority - though that intangible, reputation, is a definite factor - but from geography. In greater New York City, where 30 per cent of Harvard's last class went to work, the 1976 median income, $26,500, was 22 per cent higher than in the Moutain States. On the West Coast, where more Stanford students might be expected to settle, it was $24,000.

Traditionally those business executives who majored in liberal arts as undergraduates and topped off their education with an MBA receive the highest remuneration in the corporate world. In 1976, after one year's work, they got $25,000 a year compared with the $22,000 to $23,500 received by those majoring in natural and social sciences. Half of the 1977 Stanford class had a humanities background; at Pace University, 35 per cent did.

Surveying remuneration on a wider spectrum of B-schools, the College Placement Council found that the national average annual salary offered between September 1976 and June 1977 was $16,920 for the MBA with a non-technical undergraduate degree and $18,036 for the grad with a technical background. The apparent discrepancy between the MBA and CPC surveys probably is explained by the large response MBA received from prestigous private institutions. But for business as a whole, the CPC figures may indicate - as some educators have noted - an oversupply of generalist MBAs and a demand for those with technical knowledge.

Other factors affecting salary are age and work experience. Those Harvard MBAs who entered fresh from college received an average salary of $21.948 to start, while those with five or more years in the work force before getting the degree commanded $25,875 afterwards. The optimum age group at graduation is 25 to 29. At Harvard, the median salary for 1977 grads of that age was $22,000; for those over 30, it rose to $25,000.

However, the advantage seems to dissipate in the early 30s and/or with 10 years work experience. Those MBAs interviewed who were sponsored by their employers and/or attended part time reported little financial gain as a direct result of the degrees. Lincoln Cathers, who in 1976 received Sloan's master of science in business - "I always list it as an MBA because people don't recognize it" - was hard pressed to say how it had helped him specifically in his career as an architect for the Navy Department in Washington. Cathers, now in his early forties, is charged with managing development of design specifications for a cruiser. "I'm at the top anyway," he said. "Yet, if I'd done it five or 10 years ago, I would have gotten a promotion."

Although income levels varied considerably for grads of different schools, this was smaller than the 47 per cent variance between the MBAs' average starting salary and that of their counterparts with bachelors degrees. In 1965, the differential was only 27 per cent.

That combat begins for most B-school students in January of the second year when the recruiting season arrives, although a fortunate few are hired during the first year. Students who have survived the rigors of getting into B-school (Stanford's rejection ratio is 13 to 1, for instance), competing with their colleagues and passing exams, now find themselves in the opposite position as corporate recruiters compete for their services.

Anita White, a black Stanford MBA, had more than 50 letters from corporations seeking interviews. Harvard's Meg Miller turned down a good shot at becoming the first woman vice president at the Ford Motor Co. in order to take a job in marketing with IBM because she felt the computer industry has more growth potential than the auto industry.

Despite these stunning examples, the MBA survey, entitled "Where the Money Is," revealed it isn't generally with these groups. The median incomes of blacks and females were lower than those of white males, but there was a bigger gap for females than for black men. According to the Business Women Students' Association, starting salaries for Harvard women were about $1,000 below those offered their male classmates. (In 1972, the Powell study found men earned half again as much as women.) The gap is much wider at less prestigious schools. Yet, Miller didn't seem too concerned. "I will be making $21,000 this year, and that's more than double what I was getting before I got my MBA," she noted.

In an unusual switch, 250 Harvard students chipped in $20 apiece last fall to run ads in national newspapers announcing their availability to small business. Boasting of their "calluses, not from books, but from demanding down-to-earth jobs," they appealed to the entrepreneur, venture capitalist or innovative small business exeuctive to contact them directly. Out of the 1977 B class, 11 per cent took jobs in companies ranked as small within their own industries. (By contrast, Pace's dean, Tony H. Bonaparte, describes his students' interests as functional rather than entrepreneurial; they are more likely to go into middle management of a large corporation.)

Most MBAs from the top schools who go into small business are looking to become a big fish in a small pond that eventually will become a lake. Very few seek business opportunities with limited growth potential, although the minimum reported salary from the Harvard 1977 class, $2.650, indicates one may have. The highest salary in that class, incidentally, went to a general manager, who was offered $53.150.

Two-thirds of that class took on jobs in general management, marketing and sales, or finance. Roughly the same number of grads (9 to 10 per cent) each went into consulting, investment banking, commercial banks and - for the first-year - electronics.

There was more than a 60 per cent difference in the MBA survey in salaries paid by the lowest employer, state and local government, and the highest, real estate. Management consulting continues to be the so-called "fast track," the inside route to power and wealth. MBAs who have spent more than a year analyzing and proposing solutions for hundreds of companies believe they can translate that training directly into megabucks. With the $27,000 median consulting salary offered Harvard grads to start, an MBA can pay for his or her education in two years. Moreover, a temporary consultant's job is a marvelous vantage point from which to research opportunities and entertain offers from companies for which one might like to work permanently.

Consulting is still the rage at Stanford. Last year, McKinsey & Co., New York-based management consultants with offices in California, became the single largest employer of Stanford business graduates, hiring nearly one-quarter of the class. At Harvard, the percentage of business graduates going into consulting dropped slightly from 12 to 10.1 per cent between 1976 and last year.

Fortune magazine says another fast track is investment banking because MBAs get to handle large sums of money quickly. Morgan Stanley is considered the most prestigious, but advancement reportedly is faster at Salomon Brothers.

General Motors, IBM, Seagrams, Young & Rubicam, Bristol-Myers, Du Pont, Citibank and Exxon are just a few of the companies that hire MBAs regularly. At Citibank, where two-thirds of the new professional hires are MBAs, senior personnel officer Richard Stuart called the MBA degree a good screening process. He told Forbes, "If we put a good, selective graduate business school in the job seekers' paths, then the people who get over that hurdle and through the screen will probably be better on average. That's really all the business school hierarchy does for us." And to that, add the fact that some companies restrict their interviews to those in the top third of their class.

Hiring MBAs could be likened to buying thorough-bred stock. The expensive colt will want to have his head immediately; the owner wants to train him thoroughly and only then let him run after the big money.

Thus, when Du Pont's chairman, Irving Shapiro, speaks of encouraging individualsim and "separate career paths for talented executives who don't want to climb the administrative ladder," he is speaking as an owner gazing at the finish line. Meanwhile, down in the paddocks, Du Pont's public affairs manager, Faith Wohl, talks about "starting from the bottom up. We don't have a management training program. And we have less luck with generalist MBAs who expect to start higher." Fewer than 10 per cent of Du Pont's new college hires are MBAs.

Max McCreery, who hires 125 MBAs a year for Exxon and its U.S. affiliates, admitted to the same problem. "It is more difficult to attract students into (refinery) operations because large numbers of finance majors would prefer to start at staff level. But operations is the guts of our business. The opportunity for advancement is just as good from that level. After all, our chairman, Clifton C. Garvin Jr., started out there."

The chairman of Exxon earns $641,000 a year. And he doesn't even have an MBA.