Looking at the dedicated M4A3 sprue, if you disregard the accessories and the additional HVSS parts, there seems to be enough space for both a small hatch hull and a large hatch hull. So, in the case of the M4A2, you could include the common sprue (sprue A), the 76mm turret sprue (sprue D), and the 75mm turret sprue. That would build at least 3 versions of the M4A2. You'd almost have enough parts for 2 whole tanks! But the dedicated M4A2 sprue would need to include sandshields, a British style blanket box, and a Soviet tank commander.