Gepard,
The only thing I can think of is the affects from the skin that you added to your F-16B? I do not mean to disrespect people's hard work. I have checked the photos on the download section and compare it to your photo that you have posted. It is just not the same plane (at least to my eyes).
Again, the vertical tail base on your photo has a curve down shape which close the gap between the vertical tail base and the engine nozzle. That is how it look on the real F-16 fleet without the shute section.
All the F-16B from the download section has a big gap between the vertical tail base and the engine nozzle. In addition, the vertical tail base is straight out with no down curve shape.
Sorry, it is just me... I should check it when I get home.
Cheers, again looking very nice on the terrain.