I am working on restoring a flareside and am hoping to pull out the current shotty wiring to replace it with EFI wiring and am having a seriously hard time removing the box that holds the wiring to the body, underneath the brake booster. Does anybody know how to go about removing this piece? I'm sorry if this seems like such a rudimentary question, I suppose every once and a while, something just stumps you.

I have a 1981 F100 Flareside running a 302 5L.

 

I don't know why you would want to pull the wiring just to add EFI?
You also replacing the whole wiring system?

That box holds the fuses. IIRC it should just pull out to you so you can get to the back side.
There should also be 2 hex head screws in 2 of the corners, think 8mm heads.
Dave - - - -