Fleetwood Mac version of Sorcerer?

I read somewhere that there was a rare Fleetwood Mac version of Sorcerer that sounded almost Bluegrass. IIRC I have also read that Sorcerer was considered for a couple of FM albums. I have a couple of different demos of the track but I think they are all from the Buckingham Nicks days - does anyone know if the FM version actually does exist? Apologies if this is a silly question but I have searched and searched and come up with nothing.