Hi there. I believe it is a Hohner piano 27 (alto) not one of the early metal ones but a later plastic model made when they were still made in Germany. I can’t tell you the exact year of manufacture but if you look for Lowboy and Alan Brinton they have had a number of discussions and posts around these melodicas.
I have the same one at home but it is missing the red badge near the mouthpiece end with the trademark etc. Plays fine. If you are really wanting one I might be persuaded to sell you mine.
All the best, Adam.