Muncie family spokesman Vintage Foster said Muncie died at his Los Angeles-area home on Monday from heart failure.
Muncie was the Saints' first-round pick, third overall, out of California in 1976. He played 4½ seasons in New Orleans before being traded in 1980 to San Diego, where he finished his nine-year NFL career.
In 1979, Muncie became the first Saint to rush for 1,000 yards, finishing with 1,198 and 11 touchdowns, and his 1,506 total yards from scrimmage earned him the first of his three Pro Bowl selections.
Muncie and fellow Saints running back Tony Galbreath formed what then-coach Hank Stram dubbed the "Thunder and Lightning" combination in the New Orleans backfield. Muncie's photo is among those featured on the Saints' Hall of Honor inside the club's training facility.
Saints owner Tom Benson said in a written statement that the Saints were mourning Muncie's "untimely passing," adding, "Our thoughts and prayers go out to his family and other loved ones at this difficult time."
Muncie was traded by the Saints at midseason in 1980 to San Diego, where he played 51 games and was named to Pro Bowl rosters two more times, in 1981 and '82. In 2009, the club recognized him as one of the 50 greatest Chargers of all time.
His accomplishments on the field came despite cocaine use, and in 1989, five years after his retirement from pro football, Muncie was sentenced to 18 months in prison for a cocaine distribution conviction.
Thereafter, however, he began sharing his life story with at-risk youth, highlighting his struggles with drug abuse. He created the Chuck Muncie Youth Foundation, the mission of which was to offer children mentoring, educational assistance and counseling.
"His work with at-risk youth, the Boys and Girls Clubs and his foundation were the things that really made him shine," Muncie's daughter, Danielle Ward, said in a written statement provided by Foster.
"He was a star on the football field but his most impressive work was done in the second chapter of his life where he lived his life with great transparency," added Muncie's former wife, Robyn Hood. "He simply wanted others to learn from his mistakes. He carried that message with him everywhere he went. And as a result, he changed the lives of hundreds of kids. He made a difference."
Muncie's 43 touchdowns for San Diego, and 19 touchdowns in a single season, both rank second in Chargers history, eclipsed only by LaDainian Tomlinson.
"Everyone at the Chargers is deeply saddened by the passing of Chuck Muncie, one of the greatest running backs in Chargers history," the team said in a written statement. "We will remember him as a tremendous athlete with a larger-than-life personality. It's a sad day for all of us and all Chargers fans."
In nine seasons, Muncie finished with 6,702 yards rushing, 2,323 yards receiving and 74 total touchdowns.
Ken Trahan, general manager of the Saints Hall of Fame, said Muncie was probably the most talented runner New Orleans ever had.
"Once he got the corner, to see that guy get north and south with that speed for his size was frightening," Trahan said. "Chuck could lower his shoulder and run over people, run through people as well as just run away from them."
Muncie has been nominated for the Saints Hall of Fame, which is run independently from the club, but has not been enshrined as Galbreath has. Part of the reason, Trahan said, is because members of the Hall's selection panel say the drug use that coincided with the Saints' decision to trade him also was detrimental to the club, which went 1-15 the season he left.
"Clearly he had some issues off the field and he ended up paying a price for that," Trahan said, alluding both to the damage to his reputation and his jail time. "The beauty of that is he really overcame that, grew up and became a much better person."
Copyright 2013 The Associated Press.