By the way, it was 14mm.

Also, they had a wimpy little thermostat in there. I replaced it with the beefier Subaru part.
Trans cooler install was "fun". I put it in front of the a/c condenser. I had to loosen the condenser to fit the cooler and now I can't re-attach the condenser.(without bending things) I guess I'll have to get longer bolts and leave the condenser a little bit loose.