Oh-Kay.
Mod.1 - 2 x scratch built jerry can racks added to the side-skirts;
Mod.2 - equipment/tool storage box on the left side of the turret has been cut down, with parts cut being used to make the smaller box attached to the equipment rack behind it; &
Mod.3 - the 7.62mm GPMG on the commander's cuploa has been replaced by a .50cal M2 HMG.

Guy