The info you need for the upgrades is in the ...\Data\UPCData\UPCUnitsData\UpgradePacks.upc file. The initial guns are in the .eqp file for the sub (you probably already knew that

). Not sure about career mode, but in single missions the upgrade packs file over-rides the initial info from the subs .upc based on the date (at least that's how I observed it functioning while working on the PT boat).