private: char __thiscall FileSystem::DiskDevice::GetDriveLetter(void)

Mangled name

?GetDriveLetter@DiskDevice@FileSystem@@AAEDXZ

Exported by

size	filename	version
927064	QBXMLRP2.dll	6.0 R4000 + 8
546136	QBXMLRP.dll	6.0 R4000 + 8