If you ask me, this is too full a Monty, clocking in at almost three hours with intermission. The admitted charms of the feel-good musical based on the 1997 British film about a team of unemployed steelworkers who put on a strip show to earn money are stretched thin over the course of a long evening. Still, the material is ripe for musical pickings: guys rehearsing a show lend themselves more readily to song and dance than, say, wheat threshers or political assassins. And in an era dominated by Sondheim, there’s something refreshing about an old-fashioned book musical with a catchy (if generic) R&B-influenced score. Besides, who wouldn’t root for The Full Monty, a worthy underdog that was nominated for 10 2001 Tony Awards but took home none in the wake of the record-breaking onslaught of The Producers? The show is almost as much of a luckless hero as its cadre of six Chippendale wanna-bes, who take it all off for love and money.

It’s ironic that this slightly raunchy paean to ordinary joes waggling " the goods " before their friends and neighbors should be the sweetest, most old-fangled show to pass through town in a while. Librettist Terrence McNally moves the film’s setting from Sheffield, England, to Buffalo, New York, and he underlines the journey of the show’s good-hearted proletarians from macho boneheadedness to naked sensitivity. At the beginning, the out-of-work steelworkers transfer their anger at the plant’s closing to the women who usurp their manhood, " fairies " who dance for a living, and anything that stands between them and the next beer. By the end, not only are they " man " enough to put their limited dancing skills and imperfect bodies on the line, they’re even supportive of two of the brethren who turn out to be gay. Fledgling Broadway composer/lyricist David Yazbek mixes funk and sentiment in equal parts, with the funk being far preferable. At the core of the show, though, is the odyssey of ex-foreman Jerry Lukowski — who bristles with love for his 12-year-old son but is threatened with losing him for failure to pay child support — toward responsible fatherhood. This can get so mawkish that it’s a relief when the musical lays off the heart strings and brings out the G-strings.

Indeed, the best parts of The Full Monty are the comic ones, some of them skillfully extracted from the film, a few added by McNally, including the Big Sassy Mama–type accompanist who just shows up, piano and all, when Jerry advertises auditions to put his get-rich-quick plan into motion. In the capable hands and booming delivery of Carol Woods, this stereotypical character rocks with authority and has a lot of the best, most reactive lines. Similarly surefire are the tryouts themselves, with an unsuccessful auditioner’s hilariously inept turn followed by Dreamgirls star Cleavant Derricks’s metamorphosis, as middle-aged African-American Noah " Horse " Simmons, from morose defeatist fired by McDonald’s to slightly stiff but smokin’ " funky-chicken " purveyor par excellence on " Big Black Man. "

In general, the ironic songs win out over the soupy ones, the best being " Big-Ass Rock, " in which Jerry and his soulful if avoirdupois-burdened best buddy, Dave, having accidentally rescued factory acquaintance and mama’s boy Malcolm from suicide, bond with him over ways in which they might facilitate his endeavor. " You’ve got a friend, " they harmonize in Carole King fashion while dreaming up helpfully homicidal schemes that range from tickling " your wrist with a single-edge razor " to buying " you a beer with a Drano chaser. " It doesn’t help the tender tunes that sinewy Christian Anderson, whose Jerry is the most believably working-class of the heroes, is a somewhat grating singer.

Jack O’Brien is at the helm of the likable production, with some muscular dance turns by Jerry Mitchell, including the first-act finale, " Michael Jordan’s Ball, " in which the choreographically impaired would-be wigglers devise their routine from quick-footed, high-jumping, interweaving basketball moves. And Robert Westenberg, a Drama Desk Award winner for his salacious Wolf in the original Into the Woods, gives a subtly consternated performance as Harold, the MBA trapped into the role of strip-team player coach, that is funnier than the more aggressive turns.

In the end, The Full Monty follows twitching backsides with obscuring back-lighting. So don’t head for the Colonial if where you really want to be is Route One. But if you’re more interested in a big heart buoyed up by some saving drollery than in what the show, in one of many euphemisms, calls a " big bundle, " you’ll have fun.