It lacks the universal appeal that caused millions of television viewers to become fascinated by the question "Who Shot J. R.?" But in Washington, with its special appreciation of the fine points of bureaucratic knife fighting, the incoming Reagan administration's production of "Who Leaked What?" is proving to be an almost equally engrossing saga.

The cast includes a group of young, ultra-conservative Republicans who spent four years in the opposition wilderness skillfully using the press leak as a weapon to wage guerrilla warfare against the Democrats in the White House.

Now they are the central characters in a political drama that turns on the questions of whether they can adjust to being on the winning side and break their old habits or whether they are turning their particular talents to trying to discredit Republican moderates as part of a campaign to win control over the new administration's foreign policy.

The story began to unfold several days ago with a series of leaks, mostly to The New York Times, about some Reagan transition team members' preliminary recommendations on future policy directions. It reached a flashpoint Saturday when, in an apparent attempt to embarrass Sen. Charles Percy (R-Ill.), secret cables were leaked to the Times describing Percy's recent talks in Moscow with Soviet leaders.

In yesterday's installment of the story, The Washington Star led off with a front-page article quoting an unnamed "top Reagan official" as saying the Percy leak came from John Carbaugh, an aide to archconservative Sen. Jesse Helms (R-N.C.) and a leading member of the rightist network of Capitol Hill aides that calls itself "the Madison Group."

Carbaugh angrily denied the charge and demanded the opportunity "to prove my innocence" by taking a lie detector test. By the end of the day, the air was filled with charges and countercharges -- all coming from sources who insisted on remaining anonymous -- about who the culprits really were.

Some insisted that the leak had come from the State Department transition team of which Carbaugh is a member; some hinted it could be traced to Democratic staffers on the Senate Foreign Relations Committee who are disgruntled at the prospect of losing their jobs when the new Republican majority takes over next month under Percy's chairmanship, and some, who are Carbaugh partisans, said the charges against him were a "smear campaign" orchestrated by what one called "discredited Ford administration retreads" trying to put the young conservatives in disfavor with the Reagan team leaders.

The president-elect's senior foreign policy advisers appeared to be trying to stay above the battle, deploring the leaks while insisting that the transistion was proceeding smoothly and without internecine warfare between Republican factions. Some tried to dismiss that matter as a "boys will be boys" sort of incident.

That was the tack taken by Reagan's chief foreign policy adviser, Richard V. Allen, who offered a tongue-in-cheek solution for dealing with the problem. "We've instituted a conspiracy hour," he said. "Anyone who wants to have his conspiracy considered has to have it inscribed on the agenda by quarter to 10 each morning. Otherwise, forget it."

Still, beneath the levity, some sources familiar with the workings of the Reagan camp said there is a definite rivalry between the "Madision Group" and the "retreads" who served under President Gerald R. Ford and, to a lesser extent, his predecessor, Richard M. Nixon.

In addition to Carbaugh, "Madison Group" members holding key positions in the foreign policy and national security transition apparatus include such former congressional staffers as Richard Perle, Michael Pillsbury, William Schneider, David Sullivan, Angelo Cordevilla, Sven Kraemer and Mark Schneider.

According to the sources, they want to outflank undercut the influence of old Ford hands such as William Timmons, deputy director of the transition, and Tom Korologos, director of congressional relations for the transition. As part of this effort, the sources continued, some of these young conservatives have been leaking transition policy papers reflecting their views in an effort to foster the impression that these are the ideas that will predominate in the new administration.

The sources said a key figure in this process has been William Safire, a conservative-leaning columnist for the Times who last week wrote a generally admiring article about the "Madison Group." Safire, the sources said, has been the conduit through which most of the transition reports have been leaked to the Times.

However, the sources were divided intheir opinions about how seriously the struggle should be taken. For one thing, they noted, those reports that have been leaked so far are "first-cut efforts" by individual transition team members, and there is no guarantee that they will be accepted as the basis for Reagan's policies.

As one source put it, "Sure this kind of thing is going on, but it doesn't mean anything because it's not going to alter the outcome. In the end, the policies and personnel that represent the Reagan administration are not going to be what gets printed in the newspapers but what Gov. Reagan and whoever he chooses as his secretary of state decide they'll be. Making a lot of noise through leaks isn't going to affect that one way or another."

Another source added: "The whole thing is overblown. This isn't 10 years ago when there was a real liberal-conservative split in the Republican Party. Is's kind of ridiculous to claim there are big ideological differences between these Young Turks and someone like Bill Timmons, who was a founder of the Young Americans for Freedom. Sure it's true we've got some professioanl factionalists in here, but we don't have anything that could be called a factional situation."

Another source said, "What do these people think they're accomplishing by these leaks? You tell me. Maybe the only way to get the answer would be to add a psychiatrist or two to the transition team."