13mm square drain socket for Subaru differential

The 13mm square sockets are made specifically to fit Subaru diff plugs. Don't use a half inch socket unless you want to risk stripping your diff plug. If you strip the diff plug, then you're in big trouble. Some people get away with it ONCE, but there are plenty of people that have ended up with diff plugs they can NEVER get out. The 13mm square drivers are not cheap, but neither is getting your diff plugs drilled out and replaced. DO IT PROPERLY.