AUSTIN, Texas — While public debate raged over who should play Southern belle Scarlett O’Hara in “Gone With the Wind,” producer David O. Selznick was trying to figure out how to get the movie past Hollywood’s morality censors by tamping down the novel’s racist overtones while portraying the South in the Civil War.

Thousands of fans sent letters about wanting to play Scarlett, and the Ku Klux Klan offered to serve in an advisory role on the film. Black activists implored Selznick not to make the movie, with the African Youth Congress calling it “un-American, anti-Semitic, anti-Negro, pro-KKK and a glorification of Southern lynch society.”

Of course, Selznick pressed on and made one of the most popular films in history. And today, hundreds of items that he saved, including dresses worn in the film, scripts, story boards and other things, will go on display at the University of Texas’ Harry Ransom Center as part of a 75th anniversary tribute, “The Making of Gone With the Wind.”

The Selznick collection is one of the largest at the Ransom Center, which has been gearing up for the exhibit for about four years. In 2010, the center launched a fundraising campaign to help preserve several of the original costumes. That effort raised more than $30,000 with donations coming in from across the globe.

Among the costumes on display will be three original gowns worn by Vivien Leigh as Scarlett, including her iconic green curtain dress.

The exhibit, which runs through Jan. 4, 2015, takes visitors on a journey from the 1936 purchase of movie rights through production and the film’s eventual premiere. It examines the casting of the moving and the decision to remove any mention of the Klan from the screenplay and avoid the use of racial slurs, which Margaret Mitchell used throughout her novel.

Selznick’s insistence on barring racial slurs, most notably the n-word, likely saved the movie, said Steve Wilson, the Ransom Center’s film curator.

“If that word had stayed in, it would probably have been so offensive we wouldn’t even be watching it anymore,” he said.

Censors also warned Selznick not to include scenes depicting rape or even the pain and trauma associated with childbirth.

Much of the exhibit is dedicated to the casting of Scarlett and the rumors that swirled about the candidates from Bette Davis to Katherine Hepburn before Selznick finally settled on British actress Leigh.

Several letters in a section titled “I am Scarlett” showcase the personal connection Southern women felt with the Scarlett character, Wilson said.

The letters included hard luck stories from women who detailed their low-income or even homeless living conditions, or heartbreak in their personal lives. One woman got an entire town to do a letter-writing campaign on her behalf. Selznick’s crew received more than 75,000 letters by the end of 1936.

“There’s something in this character that really grabbed people,” Wilson said. “A lot of women feel they are right to play the part because they’ve had the same kind of romantic problems Scarlett had. More often it seems they’ve had the hardships Scarlett survived.”

In one telegram, the United Daughters of the Confederacy noted that the group would “protest vigorously against any other than a native born Southern woman” for the part.

But Southern critics soon decided that Leigh wouldn’t be a bad alternative, Wilson said.

“Better a foreigner than a Yankee,” Wilson said.