When Michael Bennett's "A Chorus Line" debuted in 1975, it broke new ground in the musical theater genre.

For the first time ever, showgoers could see a musical production from its birth. Eighteen dancers at an audition are encouraged to unveil their childhoods, insecurities, sexual identities and motivations to an omnipotent Bob Fosse-inspired director (who spends most of the show unseen, talking godlike from a loudspeaker out of sight).

The show ---- with music by Marvin Hamlisch, book by James Kirkwood and Nicholas Dante and lyrics by Edward Kleban ---- featured a spectacular chorus-line finale, "One," and some songs about breast implants and venereal disease and frank language and situations that shocked audiences of the time. It also picked up the 1976 Pulitzer and Tony awards and was one of the longest-running musicals in Broadway history (6,137 performances before it closed in 1990).

Fast-forward more than three decades and "A Chorus Line" is back. A new revival is in its second year on Broadway and a national tour is playing through Sunday at the San Diego Civic Theatre. The touring production highlights both the strengths of "A Chorus Line" (its music and its in-depth character development) and its weakness (a book and choreography that have grown dated).

But you can't fault the energetic, triple-threat tour cast who bring the story to life each night. The high-kicking, strong-voiced men and women bring a joy and energy to the show that almost make up for what's lacking in the script.

"A Chorus Line" is set at a dancer's audition for a musical in development and nearly two dozen young dancers are being put through their paces to make the cut. The director, Zach, narrows the auditioners down to 17 and then he asks each one a few personal questions to explore their personalities. Only eight dancers will make the final cut and the bulk of the show involves the dancers' inner and outer monologues and songs about themselves and their desperate desires to land the part. While the musical digs deep to explore the personalities of each dancer, the irony of the story is that each auditioner hopes to subvert their unique personality to become part of the anonymous closing kickline.

The story is set in the mid-'70s and the costumes, script and choreography reflect that period. Topics that may have shocked audiences three decades ago are hardly controversial now, though.

So when the Puerto Rican dancer Paul (played with heartfelt grace by Paul Santos) has a near-breakdown describing how he performed at a drag club to make ends meet, his hysterical tears feel a bit overwrought. The same goes for the scene with foul-mouthed Val (Natalie Elise Hall in a scene-stealing performance) who sings about taking the then-out-of-the-ordinary step of buying breast implants to improve her audition chances (the infamous "tits and ass" song, or "tits and oss" as Hall sings it). Nowadays, it's the rare starlet that doesn't opt for implants or other plastic surgery.

And while Bennett and Bob Avian's original choreography has been faithfully re-created by Baayork Lee, it all seems a bit ho-hum compared to today's gravity-defying, hip-hop, athletic choreography seen on any number of televised dance contest TV shows. Period choreography is fine, but the show's extended solo dance scene for Cassie ---- the director's ex-girlfriend who has returned from a failed star-making bid in Hollywood to humbly audition for a chorus role ---- doesn't have any of the fireworks that you'd expect to see from this allegedly "star" dancer.

Several cast members stand out in the production.

Gabrielle Ruiz has pluck, personality and power as the tough-skinned Bronx dancer Diana Morales, who gets one of the show's best numbers, "Nothing."

Emily Fletcher has the spoiled diva persona down cold as Sheila, the sexually aggressive but aging dancer who's losing her spark but not her sense of humor.

Jessica Latshaw and Colt Prattes are a funny tag-team as the married dancers Al and Kristene. Denis Lambert channels Carmen Ghia (from "The Producers") as the droll gay dancer Greg. Clyde Alves and Anthony Wayne have boundless energy in their dance solos as Mike and Richie, respectively. Ian Liberto embraces the weirdness of his outspoken chatterbox character Bobby. And Hollie Howard has one of the best voices in the show as the San Mateo-born dancer Maggie. Michael Gruber has the right sense of authority as the director Zach, but he's a much kinder, gentler version than I've seen before.

"A Chorus Line" is staged without an intermission, and with a two hour, 10 minute, running time, that may sound like a long sit. But director Bob Avian keeps the pacing smooth and the dancers are so good at their jobs that just watching them perform makes the time pass easily.

"A Chorus Line" has been lately billed by promoters as "The Best Musical. Ever." That may be wildly overstating the case. But it is an interesting time capsule of a time and place on Broadway before the era of AIDS, revitalization, Disney-ization and celebrity cameos. And thanks to a strong cast of singers, actors and dancers, it's a nice way to spend an evening in San Diego.