In the pic that looked like it was taken on the set of the comedy, Kutcher posed with Shepard with a beer can in his hand.
"Reunited with an old buddy," he wrote, adding the hashtag #notpunkd, referring to Shepard's appearances on the first season of Punk'd with Kutcher. Shepard also appeared in an episodes in 2007 and 2012.
Permanent cast or guest spot? Either way awesome addition to a great show.— Jeremy Arts (@jaydog426) March 16, 2018
One fan who saw the bromance photo asked, "Permanent cast or guest spot? Either way awesome addition to a great show."
While Kutcher has yet to respond to the fan's tweet, earlier this week it was reported that Shepard would join the cast as a recurring character following Danny Masterson's exit.
Deadline first reported the casting, adding that Shepard will play Luke Matthews, a former soldier who arrives in Garrison with history linked to the Iron River Ranch. He meets the Bennett family and quickly becomes friends with Colt (Kutcher) and Beau (Sam Elliott). However, Luke has a past he cannot escape.
Although Shepard's arrival to The Ranch comes just months after Masterson was fired, Shepard was not cast as a series regular or considered a full-time replacement for Masterson like Kutcher was for Two and a Half Men's Charlie Sheen. Shepard is already starring in a Fox pilot called Bless This Mess with Lake Bell.
Deadline reports that Shepard will star in at least five of the next 10 episodes of the series heading into production this year. The Bless This Mess pilot will be filmed in June.
Shepard has not commented on the casting himself.
Shepard's casting comes months after Netflix announced the firing of co-lead Masterson in December. Multiple women accused Masterson of rape, and the women claimed the Church of Scientology warned them to keep quiet about the allegations.
Netflix was widely criticized for not firing Masterson as quickly as it did Kevin Spacey after allegations of sexual misconduct against the House of Cards actor surfaced last fall.
"As a result of ongoing discussions, Netflix and the producers have written Danny Masterson out of The Ranch. [Monday] was his last day on the show, and production will resume in early 2018 without him," Netflix said in a statement in December.
Kutcher recently appeared on Shepard's new podcast called Armchair Expert, which has also featured wife Kristen Bell, Ellen DeGeneres, Adam Scott and Jimmy Kimmel. In the Feb. 14 episode featuring Kutcher, Kutcher talked about embracing his thinning hair.
"I started getting very concerned when I was 25, and that's when I went on the Avodart. And I think like, five years ago I stopped and I did really good for a year, and now it's thinning out," Kutcher told Shepard. "I've actually become comfortable with it. I'm just good with it. I've got kids now."