A Washington cabdriver who pleaded guilty to manslaughter was sentenced yesterday to five years' probation by a D.C. Superior Court judge who asserted that prison was no place for a 57-year-old man suffering from asthma, gout and other diseases.

The cabdriver, William Lewis of 5107 Southern Ave. SE, had been charged in connection with the shooting last June of Stanley James Weldon, 33, a laborer at the D.C. Department of Environmental Services landfill. The manslaughter charge carries a penalty of up to 15 years in the penitentiary.

Lewis' attorney, Sally Brown, argued in court yesterday that Lewis was "not a proper candidate for a penitentiary," citing his age and ill health. Brown said Lewis was taking medication for gout, asthma and dizziness. Lewis also suffers from chronic alcoholism, according to court records.

Despite strenuous objections from the prosecutor, retired judge W. Byron Sorrell gave Lewis five years' probation and ordered him to work 20 hours a week in community service activities and undergo treatment for alcoholism.

Sorrell said it was "awfully difficult not to extract some incarceration for taking another man's life," and that he was not "satisfied" that he was not sending Lewis to prison.

But Sorrell said that if he believed only "a minuscule part of reports" about prison conditions, he was "satisfied that Lewis cannot reasonably survive a period in a penitentiary."

Sorrell said another factor in his decision was that there had been no trial in the case and it was not clear if the cabdriver had fired the fatal shot in an effort to defend his son, who had grappled with the slain man shortly before the shooting took place, from being attacked.

The prosecutor in the case, Assistant U.S. Attorney William Nussbaum, argued in court for a prison term, pointing out that Lewis has two prior convictions on gun-possession charges--one in 1965 and another in 1972--and prior charges involving alleged gun-law violations dating back to 1946.

"If he was well enough to have a gun, run out of the house and shoot a man dead," Nussbaum said, "then he is well enough to take responsibility for his actions."

Initially charged with murder, Lewis already had been allowed to plead guilty to a lesser charge, in part because of his age and health. Taking those factors into account a second time amounted to an inappropriate double advantage, Nussbaum contended.

At a sentencing hearing last week, Nussbaum had suggested that Lewis be sent to a federal penitentiary in Missouri, where he could receive health treatment. Sorrell, however, said that would pose too much of a hardship for the guilty man's family.

"What about Weldon's family?" Nussbaum retorted.

Yesterday, coincidentally, marked the second time in one week that lengthy jail terms had been rejected for admitted or convicted slayers. Last week, Judge Eugene N. Hamilton ordered a 25-year-old cabdriver to serve five years on probation after he was convicted of murdering a motorist with whom he had argued over a traffic incident.

That cabdriver, Dalton Hawkins, had no previous criminal record, was working three jobs prior to the killing, had two mistrials before he was finally convicted and suffered a mental breakdown during the first of the three trials. Hamilton did order Hawkins to serve one year in prison for a firearms violation. He could be eligible for parole on that charge in four months.

The shooting incident for which Lewis was sentenced yesterday occurred after Lewis' son Eric, 26, also a cabdriver for the Executive Cab Co., had a minor argument with Weldon at a stoplight about a mile from the Lewis home, according to court records.

Weldon followed the younger Lewis home and the two engaged in a fistfight in front of the apartment building where Lewis lived, according to court documents.

Lewis eventually broke free and ran into the building. Weldon returned to his white panel truck and began to leave when Lewis reemerged from the building with a brother and his father.

Weldon got out of the van after Eric Lewis threw a crowbar or tire iron through the vehicle's open window, according to court records. Weldon was standing about five feet from the Lewises when William Lewis pushed his son aside, pulled out a .22-caliber revolver and shot Weldon once in the heart, according to court records.

Weldon's friends and coworkers said yesterday that they were stunned by the sentence.

"Good God," said Ron East, Weldon's supervisor of five years, when a reporter told him of the sentence. "I'm shocked and can't believe the sentence today. Probation? It just makes you doubt our criminal justice system."

East described Weldon, a former marine, as a "good guy" and a "decent worker." He said Weldon did not have a violent temper, but was "an impulsive type" who sometimes didn't "look before he leaped."