Age/model of old Hohner

I love my two Hohner Concerto III 34/72 accordions with their beautiful musette tuning. I just acquired from a private party this older, one-owner 34/80 in wonderful condition and in good tune. I’m trying to determine its model name so I can use the serial number to get more info from Hohner. Can someone help me with its model name? Thanks/Danke!

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