Before shooting the 1978 classic, Travolta was a 24-year-old TV heartthrob on Welcome Back, Kotter, while Newton-John was a huge music star, with a string of Top 10 hits.
The two recently celebrated the movie’s 40th anniversary with exclusive interviews to PEOPLE.
“They were desperately looking for a Sandy,” he said. “I said, ‘There is only one person that should play this role and it’s Olivia Newton-John…She’s every guy’s dream.’”
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Forty years later, the pair are still good friends.
“We text!” said Newton-John of their bond. “We did something life-changing, making that film. I feel grateful to have worked with him.”