Hi,
If a vehicle carries a cross or not, could have been decided at the factory, see the attached photo of a HPzZa in approx late 43 to early 44, a collection depot that took in new vehicles from the factories and then issued them to various combat areas, but not necessarily immediatly to combat units, that would be later.
So combat units and their camouflage applications have not yet had an affect on these StuG's current paintwork.
All these StuG's are new, and all from the same factory, but some have crosses and some do not, especially the rear hull cross, which even if its applied can be in different poistions from vehicle to vehicle.
So much for quality control

.
cheers lennard