Finally found from the bottom of the treasure cascet in Swedish Music -- Silver Mountain, making a undeadly cover of "Highway Star". Although not yet proven, this outtake may very well come from their secret studio in Luxemburg... This is awesome!
Silver Mountain 1982:
Jonas Hansson - Guitar & Vocals
Jens Johansson - Organ
Per Stadin - Bass
Anders Johansson - Drums