They had been on trial since last December, accused of complicity in the persecution of union leaders at the plant during the 1976-1983 military dictatorship. The court said both men "were necessary participants in the illegal deprivation of liberty, aggravated by the use of violence and threats" with the aim of political persecution. It found that Sibilla was also present during a torture session.
Prosecutors had requested the maximum penalty of 25 years in jail for both men.
"It's a vindication of the Argentine labor movement, which was a principal target of the dictatorship, with the complicity of the companies," said Tomas Ojea, a lawyer for the victims, after the sentence was read.
"The next step will be against the company itself," he added. "We are going to evaluate the steps to be taken to hold the company to account. It has to explain its actions." The court heard testimony from dozens of people including Pedro Troiani and Carlos Propato, who were trade union leaders at Ford in Argentina when they were detained in the factory and tortured by the military junta.
They were held prisoner for two years and letters were sent to their families claiming they had been fired for failing to show up for work.
Sibilla and Muller are currently out under a former of conditional release that bars them from leaving the country, but the judge said they would have to serve out their sentences in prison once all appeals have been exhausted. Survivors and relatives burst into applause and cheers when the verdict was given.
The court also sentenced a former general, Santiago Riveros - head of the secret Campo de Mayo detention center where the men were held - to 15 years in prison. He has previously been convicted of crimes against humanity.
Before the sentence was read, only Muller, the manufacturing manager, availed himself of the opportunity to address the court.
"I have a clear conscience because nobody can accuse me over my conduct," he said.
The case marked the first time executives of a multinational company had been put on trial for crimes committed during the dictatorship.
The company itself was not implicated, but prosecutors sought to demonstrate there was complicity with the dictatorship responsible for the deaths and disappearances of some 30,000 people, according to human rights organizations.
Cases have also been taken against other international automakers, including Mercedes Benz, Renault and Fiat, but only the Ford case has so far gone to trial.
When the military took over in a 1976 coup, some 5,000 workers were employed at Ford's Buenos Aires plant, as well as 2,500 administrative staff.
Twenty four of the 100 trade union delegates at the plant were taken captive in retaliation for union activism.
Several were tortured at the plant, on the northern periphery of Buenos Aires, before they were transferred to secret detention centers.