Trying to figure out who's going to be in George Bush's Cabinet is a little like playing musical chairs: Any number can play but there is only a limited number of chairs.

Two seats already have been taken (State and Treasury) by James A. Baker III and Nicholas Brady, leaving the president-elect with a dozen other department heads to name.The only guy who can stop this music is Bush.

Or, as New Hampshire Gov. John Sununu put it Wednesday at a news conference in Concord where he refused to confirm that Bush has tapped him for White House chief of staff, "A request isn't a formal request until the tall thin guy sings. And the tall thin guy hasn't sung publicly, and therefore I'm not going to comment."

Bush also is compelling his transition staff to take an oath of secrecy, but that hasn't stopped what seems like every Republican politician in America, plus assorted Democrats, pundits, bureaucrats, self-promoters and other Washington idlers, from speculating furiously, peddling inside tips and drawing up endless lists.

Here's a look at some of the names that have bubbled to the surface of these rumor rivulets. The departments are listed in order of seniority after the oldest, State and Treasury.

DEFENSE - Frank Carlucci is the incumbent. Unlike some of his Cabinet brethren, he has not been lobbying to stay on. Expressing an eagerness to return to the private sector, he is likely to get his wish. Former Texas Sen. John Tower is at the top of most lists of possible defense secretaries, unless Bush opts for a corporate chieftain to straighten out the Pentagon procurement mess. Then the talk turns to folks such as Paul H. O'Neill, chairman of the Aluminum Co. of America, or former defense secretary Donald H. Rumsfeld.

JUSTICE - Attorney General Richard L. Thornburgh was one of the late additions to the Reagan Cabinet, and the former Pennsylvania governor is eager to stay on. Bush insiders have sent mixed signals on Thornburgh's Cabinet life expectancy. Last week they went out of their way to discourage reports that Thornburgh was a shoo-in. Some names tossed about as possible replacements are William D. Ruckelshaus, a former deputy at Justice and former Environmental Protection Agency administrator, and Illinois Gov. James R. Thompson.

INTERIOR - Secretary Donald Paul Hodel, one of the few Reagan Cabinet members to serve the full second term, is certain to go. Sen. Dan Evans, R-Wash., who decided not to seek re-election, is a favorite in the rumor mills for Interior. Other possibilities include Nat Reed, a former assistant Interior secretary, and Rep. Manuel Lujan, R-N.M.

AGRICULTURE - Secretary Richard E. Lyng will be packing his bags after 21/2 years. U.S. Trade Representative Clayton K. Yeutter is on everybody's list, although he has talked about hankering for the private sector. Yeutter, regarded as an able trade rep, is a former Nebraska feedlot operator and head of the Chicago Mercantile Exchange. Others with a shot include Rep. Tom Coleman, R-Mo., former Iowa Rep. Cooper Evans and Seymour Johnson, a Mississippi soybean farmer.

COMMERCE - Secretary C. William Verity Jr., a retired steel executive and one of several short-timers in Reagan's Cabinet, has taken himself out of the picture. Heading the pack for this post is Robert Mossbacher, Houston businessman, GOP fund-raiser and longtime Bush chum. A couple of Bush's erstwhile rivals for the Republican nomination, ex-Delaware Gov. Pete du Pont and lame duck Rep. Jack Kemp of New York, are possibilities.

LABOR - Secretary Ann Dore McLaughlin campaigned hard for Bush, but is unlikely to retain the job she got just 11 months ago.

The leading candidate is Rep. Thomas J. Ridge, R-Pa., a moderate from a blue-collar district in western Pennsylvania who has tried to forge GOP ties to organized labor. He is credited with helping Bush carry the Keystone state.