I'm assuming that what you have, is a 4 inch square box (1900) and the GFCI
is mounted to the cover which has two screws attaching it to the box. You
can get 1900 boxes with a side bracket to attach to the side of a stud,
flush with the front of the stud, you then attach a single gang to 1900
reducing cover for 1/2 inch thickness sheetrock or whatever thickness you
need, then the GFCI screws to that adapter, and a standard flush cover goes
on top


Am I missing something here? The above description soulds like the
setup for exposed wiring unless there is something available for
regular non exposed wiring to center a gfi, just like there is for
exposed wiring. What I have are some single gang old work boxes that
are gangable to make into a double wide configuration. I believe that
they are the same as this:

http://www.grainger.com/Grainger/wwg...mId=1611711015