Need to redo almost the entire break system and flush besides the master cylinder, on rock auto there are options for RWD or 4WD. I know it uses RWD when the 4X4 isn't engaged, but doesn't 4X4 make it 4WD?

I'm a little confused and could use some guidance on the subject. Rears use drum brakes.

 

Does your vehicle have 4wd? If it does, Get the 4x4 parts.
If your vehicle is only rear wheel drive, get the RWD parts.