By JOE CRANKSHAW and GLORIA MARINA

Eighty-one persons have died - including 73 in a single act of sabotage - and scores have been injured this year in 54 incidents that have their roots in the Cuba-U.S. "cold war" of a decade ago.

Federal authorities believe that Castro-trained terrorists, who gained their skills in the 1960s, are responsible for at least 37 bombings in the U.S. and Italy.

CIA-trained anti-Castro exiles, who also learned their craft in the '60s, have claimed responsibility for the other 17 incidents in the U.S., Spain, Panama, Portugal, Trinidad, Jamaica and Argentina.

Many of the anti-Castro operations conducted by exiles were planned and financed in Miami and conducted by Miami residents, according to authorities and knowledgeable Cuban exile sources.

AND THERE is evidence that in the past, Castro may have financed or provided supplies for at least one radical group based in Puerto Rico. That group, Armed Forces of the National Liberation Front (FALN), claimed responsibility for 34 bombings in the New York City, Chicago and Washington, D.C., area in 1976.

Federal investigators have identified one of the bombers working with FALN as Filiberto Ojeda Rios, 42, a member of the Cuban Directorate of Intelligence (DGI) or secret police. Ojeda Rios, code named "Ruben," was identified in at least nine FALN bombings last year.

With the exception of Rio, who has bee and out of Cuba several times according to police, activists on both sides seem to have been trained by the CIA or Cuba in the 1960s, or to have been trained by persons who learned their craft during the "cold war" and missile crisis of October 1962.

AUTHORITIES say they have found no dente to support the belief that either Castro, the CIA are financing any type of present terrorist activities.

The heaviest loss of life during the year came during the destruction of a Cubana Airliner en route from Barbados to Cuba on Oct. 6. A total of 73 persons died in the bomb explosion, responsibility for which was claimed by The Coordination of United Revolutionary Organizations (CORU), a militant anti-Castro group.

Dr. Orlando Bosch, a Cuban exile and CORU leader, another exile identified as a former CIA operative - and two Venezeulans are in prison waiting trial on charges growing out of the bombing.

Other incidents which claimed lives are:

- An April exile machinegun attack on two Cuban fishing boats off the Cuban coast, in which a fisherman was killed.

- The April 2 attack on the Cuban Embassy in Madrid in which two staff members died.

- A July attempt to kidnap the Cuban consul to Mexico in Merida, Mexico, in which a fisheries expert who was also a DGI officer was killed.

- The September car bombing in Washington, D.C., in which former Chilean ambassador Orlando Letelier and Roni Moffitt, an American research assistant, were killed. Investigators and a federal grand jury have been quizzing anti-Castro Cuban exiles about the murders with an eye to determining if the Chilean secret police (DINA) have employed exiles for assassinations. Authorities have questioned Guillermo and Ignacio Novo, two brothers who alternate between Miami and New Jersey, about the bombing. Both men have denied any implication in the murder.

- The Nov. 8 bombing of the Cubana Airline office in Madrid, in which two persons were killed.

Castro, in an Oct. 15 speech, blamed the CIA for most of the exile attacks. Actually it is difficult for authorities to know who is responsible for which attacks, either in the U.S. or abroad.

"WE ARE aware," said Lt. Tom Lyons, Dade Organized Crime Bureau officer charged with investigating terrorism, "that many criminal conspiracies are entered into in Dade County which culminate in terrorist attacks in Latin American countries or targets which have or appear to have some relationship with Cuba." Lyons made the statement in testimony before the Senate Internal Affairs subcommittee.

"On the other side, there have been terrorist attacks in Miami against prominent anti-Castro Cubans, and there is also some evidence that key figures in certain of the anti-Castro terrorist organizations were in reality Castro infiltrators."

Lt. Lyons did not provide the subcommittee with specifics and refused to elaborate later when questioned by a reporter.

LYONS TOLD the subcommittee that there may be as many as 105 anti-Castro groups operating in the Miami area and conducting raids outside U.S. territory. But he said he could not pinpoint specific organizations as being hard core militants because of the constantly changing membership. He explained that exiles often switch from one group to another for personal or ideological reasons.

Recent statements by Roberto Carballo, president of the Brigada 2506 Association which represents Bay of Pigs veterans, support Lyons' comments about changing memberships.

In July, Carballo and representatives of several other exile action groups met in Costa Rica with Dr. Bosch and announced the formation of CORU to wage war on Castro.

SUBSEQUENTLY, CORU announced that its members were responsible for the explosion in a. Cuba-bound load of luggage in Jamaica, the planting of a bomb in the British West Indies Company office which serves Cubana Airlines in Barbados, the attempt to kidnap the Cuban consul in Mexico, a bomb explosion in Cubana Airline offices in Panama, an explosion in the Guyanese consulate in Trinidad in retaliation for aid to Anglo-bound Cubans, and the destruction off Barbados of the Cubana aircraft.

Two Miami residents were also arrested by Mexican police and identified as participating in the attack in Merida.

But Carballo says that despite his July announcement, the Brigade has not been a member of CORU. He said although he approved of the idea of a united front, no plan or concept of operation was ever agreed upon by leaders of the member organizations in CORU.

CARBALLO added that the Brigade does not support indiscriminant acts of terrorism such as those CORU claims respnsibility for because they believe the attack should be carried directly to Castro and his forces, not aimed against impotent individuals.

What seems to be a totally new group has claimed responsibility for the Cubana Airline bombing. The group, "El Condor," is unknown to police investigators and has not played a role in past anti-Castro activities.

In December 1975, after eight bombs had exploded in the Miami area, newspapers received notices signed by El Condor which claimed responsibility for the explosions. Rolando Otero was later indicted for the bombings and acquitted by a federal court jury. He will go on trial Jan. 10 on state charges connected with the bombings.

OTERO Has denied ever using the name El Condor.

Some police investigators say that "El Condor" does not exist, and is simply an effort of someone to capitalize on confusion in the exile movement.

Cuban exile activities have not been limited to Miami or Latin American countries this year.

A Cuban exile group calling itself "Omega 7"- exploded a magnetic bomb on the hull of a Soviet Ship, Ivan Shepyetkov, in September in Elizabeth, N.J., and planted a bomb in a lower Manhattan musical theater where a pro-Castro meeting was scheduled last July.

Cuban exiles were blamed by authorities for the bombing of the Cuban U.N. mission, the Cuban Embassy in Portugal, and Soviet consulates in Costa Rica and Colombia. Earlier this month, Cuban exiles claimed responsibility for blowing up the Madrid, Spain office of Cubana Airlines.

Anti-Castro groups have begun operating out of places other than Florida, according to both U.S., Communist and exile sources. But for the time being, U.S. investigators believe that Miami will continue to serve as the center for planning and direction of anti-Castro activity in the Western Hemisphere.