If they make movies long enough, it’s a good bet they’ll dethrone the big one: “Grease,” the top-grossing movie musical of all time.

At present, Meron and Zadan have produced “Chicago” and “Hairspray,” No. 2 and No. 3, respectively, on the box office tuner chart.

John Travolta, who stars in No. 1 and No. 3, compares the makers of “Grease” and “Hairspray.” “Allan Carr and Robert Stigwood were as savvy businessmen as are Craig and Neil,” he says, “but Craig and Neil have this additional thing. They are savvy about what makes a great musical, and are more acutely attuned to the musical theater-slash-film world.”

Most recent movie musicals have disappointed at the box office. So what do Meron and Zadan know that others don’t?

“The great musicals were created for the stage, not for film,” Meron says. “It is the rare ones that you can envision and reinvent as a film musical.”

Zadan points to their training ground in the 1990s with the TV versions of “Gypsy,” “Cinderella” and “Annie.”

“If you’ve never done a musical and thrown into the lion’s den of producing one, I don’t know where you’d learn what to do,” he says.

Putting the tuners aside for the moment, the producing duo’s next movie is “The Bucket List” with Jack Nicholson and Morgan Freeman, followed by Frank Darabont’s “Fahrenheit 451.”