Sugar Ray Leonard isn't going to fight for the welterweight title until next fall at the earliest, because the two champions are committed through spring, but promoter Don King wants to talk to Leonard about a nontitle bout with lightweight king Roberto Duran.

In characteristic language, King said, "I'd love to promote a Sugar Ray bouts over a 22-month period, but that on the horizon, a magnetic personality.

"Now that he is fighting stiffer competition like Johnny Gant in Capital Centre Thursday night he is taking on a new dimension. If he beats Gant he will have a new aura of acceptability. He will have shed another layer of skin.

"He is a tremendous, tremendous drawing card. I want him on the card in Las Vegas when Larry Holmes (World Boxing Council heavyweight champion) fights the winner of the Ken Norton-Earnie Shavers bout. Leonard-Duran would sell out the stadium for us."

Michael Trainer, attorney for Sugar Ray Leonard Inc., suggested that King will have to get in a long line because his client will take on a top contender next month in a television bout in Miami and then is committed through next summer.

Trainer remarked that Sugar Ray Leonard, the boxer, owns all the stock in Sugar Ray Leonard Inc.

The Silver Spring attorney added, "From inquiries, we've learned that the champion Jose Cuevas (World Boxing Association) and Carlos Palomino (World Boxing Council) are booked through the spring. Autumn would be a good time for a title bout because that's when the networks have the most money to spend. Meanwhile, Ray will keep fighting opponents ranked in the top 10."

Technically, ABC had first refusal rights to telecast six of Leonard's bouts over a 2-month period, but that arrangement ended with unbeaten Leonard's 17th straight victory, a knockout of Armando Muniz on Dec. 9 in Springfield, Mass.

Jim Spence of ABC Sports said that network will carry a Leonard bout in March on a Saturday afternoon Wide World of Sports program and others in the spring and summer on a nonexclusive basis.

Leonard's attorney said he would be surprised if all 19,764 seats at Capital Centre for Thursday's bout are not sold by today. There will be no telecast except by the Home Box Office cable system, which has about 1 million subscribers in the nation.

Besides keeping television rights to his bouts, Leonard also reserves radio rights. He granted them for this bout to Capital Centre, which traded them to WMAL Radio in exchange for promotional spots about the fight.

WMAL will broadcast the bout beginning at 9:50 p.m.