In the late '60s and early '70s The Ambassadors were a teen--age dream: Young Count Basies in white tuxedos who mixed rock 'n' soul with the big band sound.

Girl groupies, clad in sleeveless knit tops and bell-bottom jeans, swooned, screamed and cried out in breathless devotion to their favorites on the drums, the bass, the horns. The Ambassadors were only the boys next door, but duded up and in the spotlight, they were irresistible.

In their heyday a decade ago, The Ambassadors were featured and played backup in citywide talent extravaganzas that included go-go dancers and such teen-age doo-wop singing groups as The Pearls, The Fabulettes and The Strydells. This was Washington's own Motown Revue. As The Ambassadors, they established a legacy of professionalism and hard work that teen-agers who are the new Ambassadors look up to today.

Gilbert Pryor remembers those long-ago summers of teen-age music, fun and romance. He was 13 when he and five other young friends from far Northeast organized The Ambassadors. At one point, the project grew to a 70-piece jazz orchestra.

Today, 19 years after he first played with the group, Pryor is still an Ambassador, but his role in the group is different.

Pryor, 32, rehearses a new generation of Ambassadors weekday mornings in a garage-turned-practice room in the basement of the old 10th Police Precinct building at 750 Park Rd. NW. An employe of the D.C. Department of Recreation, Pryor is now musical director of the band he grew up in.

The band, which will perform a noon concert tomorrow at Dupont Circle, is part of the recreation department's Music/Showmobile Program, a traveling entourage of teen-age entertainers. The youths, including students from the D.C. Public Schools Musical Theater program, get instruction and on-the-job training in showmanship.

Pryor coaches 17 new Ambassadors and some of the 13 other acts involved in the summer series of free concerts at downtown parks, community playgrounds and recreation centers.

On a recent day, in a muggy rehearsal room, Pryor asked students seated around him and a piano if they were committed to the arts.

"The first thing about being an entertainer is nobody knows anything about you personally," Pryor told one of his students, Larnardo Blackman, 17, who plans to study voice at Knoxville College this fall. "All they care about is, are you good, or are you bad. You've got to have a kind of charisma and that begins here in the basement."

Showmobile coordinator Raymond Gray said that money from the Summer Youth Employment Program has provided jobs for more than 180 youths who are involved as singers, dancers, musicians and stage crew members. The backbone of the recreation department's music program, however, has always been The Ambassadors.

"We used to go to all the big hotels and halls," recalled Gray, who has managed the group since its beginnings. "I used to dress them up. And when they were dressed up they played better."

In his office in the old police precinct building, dusty from renovation, Gray points to the trophies, plaques and photos that fill the walls and cases. The mementos trace The Ambassadors' history and, in a sense, a part of the history of growing up in Washington. More than 300 District teen-agers have at one time or another counted themselves as Ambassadors, Gray said.

The Ambassadors began in 1963 when friends asked Pryor to bring his trumpet to a band practice. The reason? "They wanted to be in a talent show," he says laughing, perhaps amused that the group has performed in hundreds of such shows since.

In the beginning, Gray worked with civic organizations and arranged performances for The Ambassadors at neighborhood and school functions. When he was hired by the recreation department in 1968 to coordinate summer entertainment, Gray persuaded city officials to hire the young musicians as part-time recreational aides.

"We organized a group that could do community programs, music other than just rock 'n' roll," Gray said recently. Classics such as "Misty," "Satin Doll" and "Little Darlin' " were part of their repertoire.

"Then the popularity grew and the demand grew," Gray recalled. "We played for every type of function you could name."

There were ground breakings, award ceremonies and political celebrations. These were gigs that, as musicians on the city's payroll, The Ambassadors were obliged to take. But when parents and city officials weren't looking, The Ambassadors broke loose with jam sessions in the park, talent shows at Crampton Auditorium and Cardozo, and nights of dancing on the old Wilson Boat Line when they played James Brown's greatest hits and the beat bounced over the Potomac.

Known for their ambitious arrangements, full, rich tones and their crisp musical interpretations, The Ambassadors of decades past credited much of their success to the strict study of classical theory and techniques.

Now a new set of Ambassadors is trying to catch the magic that was in the music of a generation ago. Their repertoire includes a medley of up-to-date pop tunes such as "Bustin' Loose," "Reunited" and "The Closer I Get to You."

Eric Harrell, a trombone player, is one of the promising young musicians on The Ambassadors' current roster. At 19, Harrell says he is serious about music and is headed toward a future in that field. He is majoring in music education at Howard University.

But despite dedicated musicians like Harrell, Pryor has his doubts about today's breed.

"There's a hellified difference," he says, comparing teen-age musicians today with those of his generation. "You get kids who pick up instruments now who're doing it to make a dollar. We were more interested in competing with each other, learning about music, perfecting our craft."

Pryor puts some of the blame on the economy and technology. "A lot of kids sacrifice their music to take care of their needs. We lose them to working at McDonald's," he said. "They use a lot of instruments now that virtually play themselves."

For the past several years, the group couldn't find enough youngsters who met the level of talent and professionalism it required and adults were hired to add depth.

Some Ambassadors apparently benefited from the teen years spent on the Washington concert circuit and have realized the adolescent dreams of professional careers in music, if not stardom. Lincoln Ross, who once played in Count Basie's Orchestra, and McNeal Anderson, a one-time backup player for Millie Jackson, have joined other former Ambassadors who are backup players and studio musicians for artists such as the Temptations and Gladys Knight and the Pips. Some are members of such bands as Osiris and MTUME.

Still others, perhaps compromising the gamble of a big-time career, have sought more secure jobs as music teachers in public and private schools or as part-time, free-lance musicians.

Teens now in The Ambassadors, like Harrell and Stephen Foster, 16, said they are aware of the risks and uncertainty involved in musical careers.

Foster, who's been playing the saxophone for two years, said he never wants to give up his music but plans to study computer technology, a field he believes has more job opportunities.

Harrell says he probably will teach music but would rather be a full-time performer. "The love of performing, that's why most people get into it music ," he said.

Such compromises are not uncommon. Gilbert Pryor has had to make some.

For the past 12 years, Pryor has squeezed fatherhood and classes toward a degree in music education between rehearsals and performances with The Ambassadors and with other ensembles.

However, Pryor has remained faithful to his own instrument. An accomplished trumpeter, he practices because of a professional drive--and also with an eye toward the future.

"You kind of perfect yourself, do what you can do in this market, and just hope somebody will pick you out of the mud," Pryor said.

"Everybody has a time. Maybe it's not my time yet to get in the spotlight. That doesn't mean I'm going to quit," he declared. "You deal with immediate needs and strengthen yourself at the same time."