PaK 7,5cm global upgrade

A 7,5cm PaK could be made a global upgrade.

German PzIV and Stugs would have short barrel guns untill this expensive upgrade (200MP/80-100fuel) is done.
Pionieres could then build PaK 7,5cm emplacements. 310MP/15fuel
Slightly less firepower than a 17lbs.

Without this upgrade germans would have to fight with shrecks PaK 3,7cm, and PzIII (50mm gun).

This would be historically accurate.
You could risk trying to win a quick lightning war with PzIII and early PzIV or wait for heavy guns.

Personally when building panzer 3/ stugs it should be an individual upgrades that cost FUEL, however.

for example, i could upgrade my panzer 3 from its 37mm pak 35/36 to either a long barreled 5cm KWK 39 L60 great vs tanks but eh aganist infantry, or a 75mm KWK 37 great aganist infantry but shti aganist tanks

Another good idea! :)