A lot of the Pz III J/L/N models were re-equipped with the high velocity 75mm gun.
Panzer III Ausf. N (PzKpfw IIIN)
The Pz IV was a better tank than anything the Americans had until the Pershing.
In any case we're both right in that the tactics and misuse/misallocation of hardware are what lost the battle and the war.
Have to disagree, the Pzkw IV was an old design, hard to manufacture and had flat plate armor with no sloping, whereas the standard M4 had well sloped armor.
A good gun (not superior to the US 76mm or the British 17pounder, both used on Shermans) could not make up for the IV's outdated design.
A standard Pzkw IVH had 80mm (3.15 inch) of armor on its forward vertical plate.
All shermans had 76mm frontal armor at a 30 degree angle, which is superior to the vertical plates of the ageing Krupp design.