When the Drive-by Truckers rolled into the 9:30 Club on July 15, 2006, it was the closest I’ve ever come to actually losing consciousness at a rock show. The gig was beyond sold-out, more vacuum-packed with sweaty bodies than any other supposedly sold-out 9:30 show I can remember. On top of that, the show fell on one of those spongy, airless summer nights that that can make the period between Independence Day and Labor Day in this town feel about six months long.

The Truckers didn’t give a shit, of course. Their 31-song set clocked in at just under three hours. They appeared to quaff just was much Jack Daniels and just as little water as usual. (Maybe they have some band rule about only drinking water offstage, because, you know, they seem like the kind of guys who spend a lot of time worrying about their image.) Jason Ibell, one of DBT’s three world-class singer/songwriter/guitarists, knocked us out with his gorgeous cover of the Rolling Stones’ “Moonlight Mile.” Sweat-saturated T-shirts were peeled off. When the Truckers finally let us go, we spilled onto V St. like a gut released from a girdle, gasping and delirious. It was, in other words, a near-perfect evening of rock and roll.

Fast-forward a year to last Friday night. The Truckers return to the 9:30, but they’re not the Truckers they were. Isbell has left, apparently amicably. John Neff has returned to play pedal and lap steel. Legendary keys man Spooner Oldham has joined, for this tour, at least. (He played that instantly recognizable organ part on Percy Sledge’s original recording of “When a Man Loves a Woman,” in addition to playing on hits for Aretha Franklin, Neil Young, Bob Dylan and pretty much everybody else in the Rock and Roll Hall of Fame.) The Truckers are taking stock, road-testing new songs for possible inclusion on their next record, and revisiting their catalogue through acoustic arrangements a la Bruce Springsteen on his Ghost of Tom Joad and Devils and Dust tours. Billed as “The Dirt Underneath,” these shows are meant, says primary DBT frontman Pattersoon Hood in a posting on the band’s website, to ensure the band doesn’t curdle into self-parody: “We play very loud and for many good reasons,” Hood writes. “[But] I do sometimes miss how the songs get buried in the process and have always dreaded and feared a day when the whole thing becomes a caricature of itself.”