Hi guys, I have a Cole Clark Acoustic with a 3/8" truss rod nut. Is there anywhere to buy a special one for acoustic (to go in the soundhole) like they have on Stewmac (but they don't have 3/

or will I just have to use a socket wrench?
I also have an Ibanez 580B neck on my 540R that has a brass nut as well. What size is this? I'm assuming it is in mm. I could probably get this one off of stewmac.
The only guitars I've owned before this have used allen wrenches for the truss rod so this is all new to me. Thanks