Michael J. Fox is sharing new details from his “Back to the Future” days.

Fox originally wasn’t the first choice for the now iconic role of Marty McFly. That honor went to actor Eric Stoltz, who Fox eventually replaced after the filmmakers realized Stoltz wasn’t quite the right fit a few weeks into filming.

The two actors recently met for the first time while Fox was working on his book “Future Boy,” covering the intense period of time when he worked on “Back to the Future” and “Family Ties” at the same time.

Stoltz declined to take part in the book, but Fox told People Magazine, “I’m a big fan of his. He’s really great. And particularly I’m a big Tarantino fan — ‘Pulp Fiction’ was amazing.”

“It was great. It was a great conversation. It was just two guys talking, which is what I thought it would be,” he said of their meeting.

Fox also put to rest speculation about lingering tension between himself and Stoltz, who has never spoken publicly about being replaced in the film.

“There’s all this mythology built up about this thing that happened. Was it backstabbing? Was there people conniving and being evil? No, it just was the thing that happened,” Fox said. “We had different experiences with the same situation and you absorb it and you move on.”

Fox’s career took off after “Back to the Future” but was slowed after he was diagnosed with Parkinson’s disease and took a step back from acting for most of the 2000s and 2010s.

He eventually retired from acting in 2020, but five years later he’s joining the cast of the Emmy-winning comedy “Shrinking” on AppleTV+ for a three-episode arc.

The 64-year-old started as a fan and noted that Harrison Ford’s character, Dr. Paul Rhoades, has Parkinson’s as well.

After seeing the show, Fox told the outlet he called series creator and former “Spin City” colleague Bill Lawerence and asked, “‘You did a show about Parkinson’s, and you didn’t call me?’ And he said, ‘Oh, you want to do it?’ And I said, ‘I’d love to do it.’”

Lawerence came up with a concept that they’re keeping close to the vest, but Fox is playing someone with Parkinson’s.

“It was the first time ever I get to show up on-set, and I didn’t have to worry about am I too tired or coughing or anything,” he told People. “I just do it. It was really good, because for the moments when I say, ‘I’m not going to be able to do this,’ then I say, ‘Well, I’ll just deal with how I can’t do it in the scene.’ And you get through it.”