Fahrzeugfabrik Kannenberg FAKA produced this from 1954 on as the FAKA Leichtbus SK 4,5 with a Henschel-engine, but the producer of the prototype apparently was "Stadtverkehr Willy Hohmann Wolfenbüttel", who did busservice in Wolfenbüttel until 1994. He also had a connection with Büssing, a big bus manufacturer in Braunschweig, and he went there when Danzig became Gdansk (eventually). I am not into buses at all, but I came onto this page some time ago when I was reading about Zeppelins, and this guy had been involved with them in the First World War. Anyway, you know the site it comes from, of course.