Horch firetruck

First of all, I doubt that the basis of this firetruck was a Horch 400. The design of the engine louvres is inconsistent with that model and rather points towards an earlier model (305 or 350). For reference I've attached a photo (from my collection) showing a Horch 400 two-door cabriolet. If the Horch was used by the German Lufwaffe as a kind of personnel carrier during WW2 - which is a possibility - we are probably dealing with a "one-off", since the car was seriously outdated then and wasn't used as a basis for regular conversions. There are, however, other photos from WW2 showing improvised utility cars using the chassis of old Horch 8-cylinder models. Since the Wehrmacht was notoriously short of motorcars, almost everything was possible at the front as well as behind the lines....