Time was when an election landslide like November's would have meant moving day to Bruce K. MacLaury and William J. Baroody Jr. As presidents of the city's two dominant think thanks -- the Brookings Institution and the American Enterprise Institute -- both men are used to high turnover rates during transition periods.

After the 1976 election, for example, Baroody's AEI provided a haven for no fewer than 20 fugitive Ford administration officials -- including the defeated president himself. Meanwhile, Brookings gleefully packed off five of its own stars to take over top Carter administration policymaking spots.

For years, the two institutions have functioned alternately as shadow cabinets to whichever party is in office, providing both the fodder and the staff work for the "loyal opposition." When the GOP is in power, Brookings is the government-in-exile. When the Democrats win, AEI houses the outsiders.

But this year, despite the magnitude of Reagan's win, there won't be the usual musicalchairs game at either institution. Brookings is taking back only two of the Carter administration's current inner circle -- White House economist Charles L. Schultze and international economics adviser Henry Owen.

And while Reagan's staffing plans aren't final yet, Baroody predicts the president-elect's new appointments will deplete AEI's ranks by five to 10 of its 34 resident scholars. "Oh sure, we'll have people leaving," he says. "But from everything I've heard so far, I'm not expecting any mass exodus."

Ironically, the absence of any wholesale desk-shuffling this time may be due partly to the sweeping character of Reagan's win. With the Senate going over to GOP control, the job turnover in Washington is higher than it's been in years. There's no shortage of resumes, either Democratic or Republican.

But the fact is, despite their traditional liberal vs. conservative labels, Brookings and AEI also are edging closer together in their focus: away from the moderately far left-and right-of-center, toward the more pragmatic -- and less blatantly ideological -- midpoint of the political spectrum.

At the same time, however, they're emerging with visibly different styles. Brookings remains the same gray eminence it's been for years: reliable, scholarly, seeking government solutions to problems, dealing with longer range, more academic-sounding issues, primarily through the publication of books.

Meanwhile, AEI, whose solutions inevitably involve the private sector rather than government, has begun concentrating on far more current issues and has moved aggressively to use magazines, pamphlets, seminars -- and even television -- to get those ideas across.

Last year, AEI's scholars cranked out more than 130 new publications, published four high-quality magazines -- Public Opinion, Foreign Policy and Defense Review, Regulation and The AEI Economist. And AEI's weekly public affairs TV program, Public Policy Forum, is aired on 400 TV stations.

AEI's frenetic new mode has attracted dozens of top scholars and analysts, from former Federal Reserve Board Chairman Arthur F. Burns to political scientist Ben F. Wattenberg. It is generally agreed that it has eliminated the monopoly Brookings had held for decades as the nation's premier think tank.

Brookings' impact over the years has been impressive by any measure. Its research laid the groundwork for most of the Great Society programs of the late 1960s, the "tax reform" efforts of the 1960s and 1970s, the Kennedy wage-price guidelines, and recently, the use of tax incentives to encourage wage-price ease.

Founded in 1927 to consolidate three smaller research organizations organized by St. Louis lumber magnate Robert L. Brookings, Brookings began as a fairly conservative -- and low-key -- institution, opposing the New Deal and most major government social efforts. Still, its reputation was unmatched.

Brookings' own big blossoming came in the 1960s, when -- under the presidency of the late Kermit Gordon -- a former Kennedy administration economic adviser, it began turning out proposals that provided the underpinnings of Democratic Party social policy. MacLaury took over in 1976, after Gordon's death.

AEI's acknowledged challenge to Brookings is by no means a Washington tradition. Organized in 1943 by Lewis H. Brown, chairman of the Johns-Manville Corp., to promote freemarket ideas, AEI has spent its first few decades as a virtual captive of the corporations that financed it.

As late as 10 years ago, the American Enterprise Association, as it previously was known, was widely dismissed as decidely third-rate -- more a purveyor of probusiness rhetoric than of serious analysis. Its sparse formal studies generally were regarded as suspect. And its impact was almost nil.

But in the early 1970s, Baroody's father, the late William J. Baroody, and the man most responsible for AEI's renaissance, began moving to alter the institutions character and to broaden its influence on Washington's policymaking establishment.

The elder Baroody's first step was to beef up the credibility of AEI's studies by discarding much of their predictable right-leaning rhetoric and insisting on first-rate scholarship, initially in the economic field and later in other areas. Then came the foray into TV, bolstering AEI's image.

Then, in the 1976 post-election shuffling, Baroody managed to reap a windfall. Some 20 outgoing Ford administration policymakers, all widely respected in their fields, were willing to come aboard. "We would have made it anyway, but that telescoped things," his son muses now.

The payoff was almost immediate. At a time when Brookings' prestige was slipping somewhat, AEI began attracting attention and new credibility. Money followed the overall upgrading. In fiscal 1977, AEI's budget doubled, to about $10 million. (In 1970, AEI still was surviving on only $800,000 a year.)

AEI's influence on specific issues has only begun to be measurable, but Baroody justifiably claims credit for his institution in first pointing out the need for regulatory reform, now a recognized goal of both Republicans and Democrats. And AEI studies in the budget and tax areas also have had impact.

Despite their movement toward the center, both Brookings and AEI still suffer from their party-label images -- Brookings as liberal Democratic and AEI as mainstream Republican -- although both insist they're independent and have hired staffers from the opposite party.

"The facts say there are more Brookings people who have gone into Democratic administrations," concedes Brookings' MacLaury, ironically, himself a lifelong Republican. Brookings has hired some GOPers, he says, "but it would be hard to deny" that Democrats feel more comfortable there.

Nevertheless, both organizations are making efforts to shed their partisan handles, in part because they believe it hurts credibility. "It would be a mistake, both intellectually and in terms of balance, to be perceived once again as a revolving door" for any administration, MacLaury asserts.

As it stands now, the two are about evenly matched, both financially and in size: Brookings' budget is $10.7 million, compared with AEI's $10.4 million. AEI has 34 resident staffers and a spate of adjunct scholars at private universities. Brookings has 50 resident staffers and 50 "guest" scholars.

Brookings get about 15 percent of its money from government grants for specific projects, with the rest from foundations and its own endowment, book sales, conference fees and the like. MacLaury is actively seeking more corporate contributions. These totaled only $600,000 last year.

For philosophical reasons, AEI currently won't accept government money and instead relies on gifts from corporations for 40 percent of its income and foundation grants for the other 60 percent. But Baroody cautions he's not sure how long the institution will be able to afford to make the prohibition stick.

Following the lead of private universities, AEI is now soliciting donations from corporations and individual donors who want to sponsor a "chair" or program that, in turn, will bear their name.

Ironically, for all the talk about competitiveness, the two institutions aren't totally isolated. Staffers from each often participate in the other's seminars and conferences. "But we have not collaborated as institutions," MacLaury says, by way of distinction. h

What's ahead for the next four years? Most likely, the two will be edging even closer to each other's turf, their chief executive officers concede.

Baroody says AEI is planning major forays into the political-socialogical arena, studying the impact of society's big institutions -- giant corporations, organized labor and big government -- on the family, the church and the neighborhood.

And MacLaury is hoping to launch Brookings on a major study of capital markets and financial institutions and, possibly, the introduction of a new scholarly journal -- both areas the institution has shunned before. As of this point, neither group expects a major expansion of its size and staff.

Meanwhile, AEI is rubbing its hands with glee at the new boost it sees for free-market prescriptions as a result of the Nov. 4 election. Will 1980 do for conservatives what 1932 did for New Dealers, Baroody asks? "The proof will be in the pudding," he says, "but this is an important opportunity."