Hi,
The Smithsonian National Air and Space museum in Washington has a large amount of Republic documents, including the Erection and Maintenance and parts catalog for the P-47D. You can fill out an inquiry form at their website and after that things are pretty easy and explained.
The E&M manuals are not cheap though...
I did not had any luck in finding them somewhere else.
Good luck...
Kind regards from Holland,
Sander