Are you sure this is an original De Dietrich chassis? I barely had time to be here, but ever since I saw this puzzle I have this nagging feeling. Now we know that it was bodied in Austria by Armbruster, I have a feeling this is a car which was put together by the Leesdorfer Automobil Werke in Leesdorf near Baden, which produced cars under licence from De Dietrich beginning in 1900.
In 1903 the company went bankrupt. Apparently its assets have been bought by a Hungarian company, which launched its own automobile production using these parts.