And just for information for new hobbyists and for people who might be interested to know:
The internals:
There is precious little empty space inside, the StuG is a very, very compact design. They use a different barrel elevation unit than the standard one fitted to all / most other HL tanks even, and a smaller speaker just to make sure it fits.
Another result of this thing being so compact:
A different type of battery. Up top the 9.6v, 1000mAH battery and charger for the StuG, below the 7.2v, 2000mAH battery and charger for my Leopard 2A6 (which is the same type as came with my JagdPanther and Pz IV F2).
JagdPanther / Leopard 2A6 / StuG Ausf. G / KV-2 / M4A3A4 / MTLB / 2.5 ton truck 6x6