A
Sturmhaubitze 42 with a Zündapp
KS-750 on the rear deck.
At first this appears to be a
Sturmgeschütz III
Ausf.G, but the cover over the main armaments muzzle is too big, and the gun appears to be stubby, leading me to belive this is a StuH.42.
The bike on the rear deck most likely belongs to the StuG. Batteries courier.