Police are seeking the 20-year-old son of bandleader Stan Kenton in connection with an apparent attempt to use a rattlesnake to kill an attorney who won a large judgement against Synanon, a group orginally set up to help with drug and alcohol rehabilitation.

Officers said a Synanon legal representative told them he would turn over Lance Kenton, a former Synanon member, and another man also being sought. He also promised to deliver an automobile seen at the home of attorney Paul Morantz, who was bitten by a rattlesnake on Tuesday.

Morantz, 32, won a $300,000 judgement against Synanon last month and said he had been warned after the judgement that he was on a "hit list".

Morantz was in serious condition at the Los Angeles County-USC Medical Center where he was being treated for snakebite poisoning.

Spokesman said at least one of the suspects would be arrested for investigation of attempted murder.

One of Morantz's neighbors in the Pacific Palisades area said two men driving the car in question, a 1973 green four-door Plymouth, put something in the attorney's mailbox Tuesday. He became suspicious because tape had been placed on the vehicle's license plate to disguise the number, and he discovered and wrote down the true number.

Police traced the license plate and determined the car was registered to the Synanon Foundation in Marshall, a small town north of San Francisco. The group recently moved its headquarters to a ranch there.

[Police would not say where Lance Kenton was. However, Audree Coke, Stan Kenton's manager, told the Los Angeles Times that Lance called his father yesterday morning from the Synanon camp at Badger, Calif.]

[Coke said Lance told the elder Kenton that he was being sought and that he was being flown by Sunanon staff to Los Angeles. Coke confirmed that young Kenton had lived in Synanon about 10 years. His sister, Dana, 22, also spent about a year with Sunanon several years ago, Coke said, "but she hasn't had anything to do with them since then."]

[She said Kenton would have no comment on the situation involving his son. Kenton, 66, is recouperafing from extensive brain surgery required after he suffered a fall in May 1977.]

Morantz, who represented a woman and her husband who claimed she was kidnaped and abused after seeking counseling at the group's old headquarters in Santa Monica, was bitten by the snake Tuesday afternoon when he checked the mailbox in the wall of his home on his way out of the house to go to the opening game of the World Series.

The serpent sank its fangs into his hand and helf on as he drew back, pulling the 4 1/2-foot reptile out of the mailbox.

"It felt like having my hand in a vice and it kept tightening."

Police said the snake's rattles had been cut off, apparently so it could not give a warning of its presence.

Firemen summoned to the scene by neighbors who heard Morantz's screams cornered the snake in his living room and chopped of its head with shovels.

Doctors said Morantz suffered "a relatively severe envenomation" that "most certainly" would have killed him if paramedics had not reached him quickly.

Synanon, founded 20 years ago by Charles Dederich, a recovering alcoholic, to treat drug addicts and alcoholics through intensive group sessions and communal living arrangements, has grown into an $3 million empire.

While the group orginally was dedicated to nonviolence, a spokesman recently announced the group had amassed $50,000 in firearms and ammunition for a private police force to fight "an escalating pattern of violence" against Synanon facilities.

There have also been reports by police in several cities of threats against reporters and news executive connected with articles and broadcasts that Synanon disliked.