I've noticed that stegosaur skeletons (eg// _Kentrosaurus_ at the BMNH, photographs of _Tuojiangosaurus multispinus_ and _Huayangosaurus taibaii_ specimens in the section on Asian stegosaurs in "Dinosaur Systematics") seem to be mounted with the tail and neck both sloping downward, but in *illustrations* of the skeletons (eg// _Stegosaurus_ in "The Dinosauria" and _Tuojiangosaurus_ and _Huayangosaurus_ in "Dinosaur Systematics") tend to show the neck raised upwards (kind of more horse-like) and the tail raised at least level with the sacrals (instead of sloping downwards).
I had thought that it was a sign of a transition from seeing stegosaurs as giant-lizard-like things to seeing them as bird-elephant-like things, i.e. that the skeletons had all been on display like that for decades and not changed, whereas the illustrations could obviously be replaced more easily. But then i noticed in "The Encyclopaedia of Dinosaurs" that the neural spines on _Stegosaurus_ caudals are angled towards the rear of the animal, and thought that maybe that restricts the tail to a downward sloping sort of posture.
So... what's the actual preferred posture for a stegosaur's neck and tail? Why are the mounts of the skeletons different from the pictures of the skeletons?