Miami, April 8-The exiled Cuban leaders here, still preparing a thrust against Premier Fidel Castro in Cuba, are busy unfolding plans for future regimes.

These political and ideological plans reflect the deep differences and rivalries among the men and groups that recently achieved a shaky and temporary unity for the immediate purpose of ousting what they all regard as Communist rule in Cuba.

For months, groups of saboteurs and guerrillas specialists have been landing in Cuba from hidden bases in the Florida Keys. They have been laying the groundwork for the plans of the anti-Castro exiles.

The first assumption of the plans is that an invasion by a "liberation army," now in the final stages of training in Central America and in Louisiana, will succeed with the aid of internal uprising in Cuba. It is also assumed that a provisional "government in arms" will be established promptly on the island.

A parallel plan, still under study, is to set off guerrilla uprisings, backed by diversionary landings of highly trained combat units and a wave of sabotage by the underground groups. Larger landing, using the bulk of the 5,000-man revolutionary army, would them be effected to support the guerrilla movement.

Although these proposals are based on the expectation that the Castro regime will collapse in the face of the projected onslaught, the more realistic among the exiled leaders have other ideas. They accept the possibility that a bloody and perhaps long civil war will be the first phase of the anti-Castro action.

If such a war does develop, they say it will be fought politically as well as militarily. The political struggle will seek to enlist Cuban and Latin-American public opinion.

The top leadership of the Revolutionary Council, the seven-man united command headed by Dr. José Miró Cardona, accepts the premise that any future Cuban regime must continue democratically the social revolution initiated by Dr. Castro two years ago. But there are profound differences in interpretation.

Like other emigré political groups, the anti-Castro Cubans are split into a multitude of factions.

The Cubans, reminiscent of the exiled European Governments in London during World War II, suffer from what an observer called "the incurable political disease of exile."

The refugees, publishing a score of newspapers and producing a series of daily radio programs over Miami stations, openly and covertly fight each other, jockeying for positions in the future government. There are instances of men belonging to the same organizations who hardly speak to each other.

Orbiting around the democratic revolutionary group are the factions one associated with the deposed dictatorship of Fulgencio Batista, trying hard to win acceptance in what they say should be a common struggle against the Castro regime.

But the Revolutionary Council has repeatedly rejected them.

The United States was largely responsible for efforts to weed out Batista supporters from the anti-Castro groups. Today agents of the Federal Bureau of Investigation took into custody Rolando Masferrer, a former pro-Batista Cuban Senator and head of a terrorist private army.

As a part of the in-fighting, many Cuban leaders charge privately that the People's Revolutionary Movement, led by Manuel Ray, proposes to install in Cuba what they describe as "Fidelismo without Fidel," a system that would draw much of its inspiration from Leftist ideas.

A Rightist campaign is under way to discredit Señor Ray, a former aide of Dr. Castro. The campaign is being carried out especially by economic interests desiring to recover the investments they lost in Cuba through the Castro nationalization policies.

According to reliable reports, it took powerful pressure by the United States to convince the other revolutionary groups to accept the unity compact under which the Ray movement was integrated in the Council and Señor Ray received a seat on the directorate.