what rear end ??
Don is right get the wheels first, then find the rear end, I didn't ask before I built mine, so I ended up with 2" backspace wheels and 2" spacers, I dont like it, but for now it works, you can get wheels in any backspace you need from 2" and up, but not many under 2".
Good luck with the build and keep us posted, ask all the questions you need and ask first before you build and end up having to rebuild.