I PUT IN A CALL to Scott Rudin the other day to find out how the producer of “South Park,” among myriad other projects, felt about the ratings wars. Rudin’s movie had ricocheted back and forth six times between the ratings gurus and the studio before being blessed with an R rating instead of a dreaded NC-17, thus becoming one of several “hard R” pictures appealing to young audiences during this sensitive post-Columbine period.

Detailed notes of the “South Park” ratings negotiations, the specifics of which would embarrass a longshoreman, have started circulating around town, further fueling the controversy. (Where else would one encounter a debate over the etymological nuances of “rim job”?)

I realized reaching the bear-like, 40-year-old producer would not be easy. When Rudin sits down for a chat, he can be great company, since he’s an intelligent man with a churlish sense of humor, but no one has actually observed Rudin sitting down for years. In fact, best I can tell, few have actually seen him at all. It’s not that he’s unfriendly; he just has a lot on his plate.

“Between now and the end of the year, I figure Rudin will be responsible for about six movies and five plays,” says one Paramount executive who actually managed to get him on the phone recently. “I don’t think even he keeps count.”

I decided to check that out with Rudin and, sure enough, I got a message the next day that he’d returned my call at 7 a.m., which was two hours before either my assistant or I ever get to the office.

My curiosity about “South Park” had heightened after reading notes of the meetings with the ratings board. Exchanges over the so-called “code” are often vivid, if laborious, but in this case, the word “fuck” was the mildest expletive cited. The board was clearly alarmed over scatological dialogue covering everything from anal entry to a sex act involving God. The only thing they didn’t object to was the double entendre subtitle: “Bigger, Longer and Uncut,” the meaning of which apparently had eluded them.

In view of all this, it’s been no surprise that “South Park” has become a hot button at this moment in time. The plot of the animated film concerns young kids who sneak into an R-rated movie and become so caught up in its four-letter lexicon that they can’t stop using their new vocabulary. To exacerbate the problem, the co-creators of the film, Matt Stone and Trey Parker, are on record as saying that the reactions of the ratings board were “stupid,” revealing “an absence of true standards.”

SO HOW IN THE WORLD was the movie awarded an R? Rudin called me again the next day, presumably to explain. Since he’d placed his call at 6 a.m., however, we didn’t connect.

“Scott’s on a plane to London,” an aide later explained. “He knows you’ll understand.”

I did understand. Sort of. I knew he was nursing along at least two new plays: a Stephen Sondheim show called “Wise Guys” and a musical to be directed by George Wolfe called “The Wild Party.” In post-production were movies directed by Martin Scorsese, Tim Burton and Curtis Hanson.

“He likes to stay below the radar, but Scott’s more prolific than any studio,” says one producer who’s working with him. “I’d call him a force of nature, except I don’t think he likes nature that much.”

A studio executive who occasionally deals with Rudin has a slightly different story. “Scott is getting impatient with producing movies,” he confides. “Like most producers, he has to come up with at least half the financing for his films, which means he’s constantly dealing with sub-distributors all over the world.”

According to one source, Rudin told a studio chief that, since the studio was putting up only one-third of the financing, he intended to listen to only one-third of its comments.

Did that mean that Rudin, who switched his base to New York five years ago, intended to back away from the movie business? I placed a new call to verify this and, sure enough, the next morning at 5:15, he dutifully returned it. Alas, no one was in.

RUDIN’S REPUTED FRUSTRATION with the process was relevant, of course, given his remarkable track record. In the last decade, he’d had his stamp on about 26 movies, ranging from “The Truman Show” to “Ransom,” from “A Civil Action” to “Clueless.” He’d had his hits, like “The First Wives Club,” and also an occasional flop, like the remake of “Sabrina.” On Broadway he’d been a producer of “Indiscretions,” “Hamlet,” “Skylight” and the Sondheim musical “Passion.”

“Scott loves the opera, ballet and the theater,” explains one associate. “He’s become the ultimate New York prince with a giant apartment at the San Remo on Central Park West.”

The prince has his occasional tantrums, to be sure. His tempestuous relations with his assistants are legendary, and last year he became so angered with the handling of a movie premiere that he dispatched a note to a Paramount executive warning: “The only thing separating my hands from your neck is the fact that there are 3,000 miles between us.”

“Scott’s tired of reading about his tirades and even about his success,” says someone close to him. “He really only cares about the work. He still gets a rush when he finds a great piece of material. You may not believe this, but he has actually mellowed.”

Was Scott Rudin really mellowing? I decided to put in another call to check this out and, sure enough, he returned it — at 4 a.m. I hadn’t reached my office yet, so I have no idea what he intended to say.