I do not have any data on the history of the Professional 36 or even the Piano 36 so I cannot confirm when they first came out or the progression. Hopefully someone on here may have more information. As I understand, the Professional 36 came out first then the piano. I picked up my Professional 36 somewhere around 2000 (used) from a musician friend of mine. I purchased the Piano 36 about 4 years later. I wish I could find more information on these Melodicas, not even on the Hohner site do they discuss the Professional and Piano history or construction. I will post pictures late tonight.