Hi @sarbian and @JPLRepo, Above I was confused as I wanted to add the ModuleCargoPart to everything, to be able to construct (with many kerbals helping, and the Exoskeleton Mod) bases out of other parts. KSP seems to be pushing for ModuleCargoPart and ModuleInventoryPart to not be on the same part, even though the small command pods DO have this.   The Log produces a WRN: This is a fresh download, KSP 1.12.2 from Steam, Expansions removed and nothing else install (not even MM):