It's easy to pick out 12 seconds into Bob Marley's song "Bend Down Low" on Natty Dread. It joins the melody and is distinctive.
Also, it's used heavily on Ras Michael's album, "Rastafari". It joins the song, "None A Jah Jah Children No Cry", at 16 seconds very clearly.
Please help me out solving this mystery! I really want one! Me and my brother have resorted to calling it, "Jah Organ"