Hold it, these guys aren't from the '50s. They almost had us with the overalls, snap-brim hats, fiddles and stomping hillbilly honky-tonk. But with one line, BR5-49 abruptly returned to the present: "Her punk-rock records are gathering dust," they sang, "because little Ramona's gone hillbilly nuts."

Without even a wink or a sarcastic joke, this Nashville quartet pretended for two hours Thursday night that the present doesn't exist. Despite the "Ramona" line, one electric guitar and one song by the late country-rocker Gram Parsons ("Big Mouth Blues"), BR5-49 refused to acknowledge the existence of rock & roll, punk, grunge or anything post-Hank Williams Sr.

The band's two frontmen, Chuck Mead and Gary Bennett, revisited all the angles of Williams' old voice, adequately yodeling on "Long Gone Lonesome Blues" and moaning on "You Win Again." They also matched George Jones' goofy baritone in "White Lightning," Ray Price's bluesy crooning in "Crazy Arms" and Lefty Frizzell's sad storytelling in "Long Black Veil."

BR5-49, named after a fictional telephone number from the television show "Hee-Haw," is a reverential country jukebox, able to reproduce country classics without hesitation. Smiling constantly -- especially the frantic upright bassist, Smilin' Jay McDowell, dressed in a purple suit -- the musicians gamely announced they would play as many requests as possible. (Of course, true to their schtick, they asked for "green" in an onstage tip jar for each request.)

Tagged by no less than the New York Times as figureheads for the growing "alt.country" (or "no depression," or "twangcore") movement, BR5-49 finds inspiration in the past much more than the present. Notably absent from its versatile set list was new country -- if punk didn't exist Thursday night, Garth Brooks REALLY didn't exist -- aside from such originals as "Bettie Bettie," "Little Ramona (Gone Hillbilly Nuts)" and Billy Joe Shaver's more recent "Georgia On a Fast Train."

Some say this music constitutes a weird form of punk because it's rebelling against the slick hits on country radio. But aside from Bennett's bad joke exhorting the shoulder-to-shoulder crowd to "slam-dance!" the two-hour show didn't seem rebellious at all. What makes BR5-49 such a terrific live band is its lack of sarcasm, unashamed charisma, enthusiasm and tight playing.

Mead looks like a pockmarked Robert Redford with shaggier hair. The more reflective Bennett complimented a fan on a T-shirt and, upon hearing somebody shout, "Gary!" shot a puzzled look into the audience. Overalls-clad Don Herron smiled like a dippy hillbilly, but sang and played steel guitar, mandolin and fiddle -- sometimes holding two instruments at once -- and effectively earned his nickname "The Professor."

But the band's secret weapon is its rhythm section, McDowell and drummer Shaw Wilson. On Webb Pierce's "I Ain't Never," covered on BR5-49's self-titled 1996 debut, the musicians tapped out a strict, thumping Buddy Holly rockabilly beat. The trucker classic "Eighteen Wheels and a Crowbar" was a deeper, more ominous groove, and the encore of "Sweet Georgia Brown," "White Lightning" and "Big Mouth Blues" moved quickly from swing to country-western to, finally, rock & roll. The microphones gave out at the end.