Currently in the studio working on their fourth disc, Stone Sour announced the official departure of bassist Shawn Economaki in early May. With Economaki out of the picture and the bassist position wide open, it begged the question - who would be playing bass for Stone Sour moving forward?

While a permanent replacement has not yet been announced, the band would only say that they had “a mystery dude that shreds filling in for the studio,” posting a fuzzy photo of their mystery guest.

It appears the cat is out of the bag though as Skid Row bassist Rachel Bolan checked in on Twitter at the beginning of May letting fan’s know he was recording with the band, saying, “Horns way up this week. I’m in the studio recording with Stone Sour. Playing bass on their new record.” Bolan also called the new Stone Sour material “f---ing fierce.”

In a new interview with The Backstage Beat Bolan talked about the new gig in a bit more detail. He explained how it all started, saying, "Just out of nowhere, my phone rings one morning, and it's Corey Taylor from Stone Sour, and he's, like, 'Would you be interested in playing bass on the new Stone Sour record?'" He continued, saying, "So, of course, I said 'Yes,' 'cause I'm a huge fan of the band and they're all really, really great guys."

Bolan said that he's already recorded 19 songs with Stone Sour and has five more to go.

With Bolan busy with his own band Skid Row, this seems like a temporary engagement with the touring bassist position still up for grabs, but until Stone Sour announces an official bassist anything is possible.

The new Stone Sour disc from has been described as an ambitious concept album that may even span two discs and close to 30 tracks. Producer David Botrill, who has worked with Tool in the past, has been tapped for the record.