What i cannot find in the rule book is how to upgrade it.
Often one must string several areas of the Rulebook together, which can be hard to find.
AAE40 Rulebook Page 24> Industrial Complexes>Unit Characteristics> Tells us the upgrade price= $20IPC (and limits, example- Territory value 3IPC or greater, have to own it at start of turn to use it, etc).
AAE40 Rulebook Page 12>Phase 1:Purchase & Repair Units - This tells us when we can buy the upgraded Ind. Complex and where to put it for now (Moblz. Zone)
AAE40 Rulebook Page 22> Phase 5: Mobilize New Units -Tells us that "place new facilities" is when we put the Major IC chit on the game board territory, as well as some limits to placement.
Hope this helps.