Farrah Fawcett and Ryan O'Neal to Wed

Celebrity News June 22, 2009 AT 9:58AM By UsWeekly Staff

Ryan O' Neal and Farrah Fawcett attend the Share, Inc., 51st Annual Boomtown Party at the Century Plaza Hotel & Spa on May 15, 2004 in Century City, CA. Credit: Frederick M. Brown/Getty Images

Ryan O'Neal says he and longtime love Farrah Fawcett are tying the knot.

"I've asked her to marry me, again, and she's agreed," O'Neal, 68, tells Barbara Walters in an exclusive interview on ABC's 20/20, airing Friday, June 26.

O'Neal says the 62-year-old Fawcett - who was diagnosed with anal cancer in 2006 - is now "fighting for her life."

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But he says they "will" wed "as soon as she can, say yes. ... Maybe we can just nod her head." "I promise you, we will," he told Walters. "Absolutely."

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The actor says he and Fawcett have even joked about what he'll wear for the ceremony, kidding that he'll dress "like a gigolo. You know? And a little thin mustache and slicked-back hair. I don't know. We have fun, we tease about that."

The two -- who have a 24-year-old son Redmond (who is now in rehab following previous drug convictions) -- began dating in 1980 and have lived together.

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"I used to ask her to marry me all the time," O'Neal tells Walters. "But ... it just got to be a joke, you know. We just joked about it."

In May, O'Neal told NBC News that he has fallen more in love with Fawcett as he watches her bravely battle cancer.

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"I know this, that in the last two years I loved her more than I've ever loved her - ever," he told Meredith Vieira. "She's so much more of a woman ... powerful, courageous, fearless and all those adjectives. And I look at her with awe."