new to the dually scene need advise on narrowing the rear end

i have 2005 f 350 slammed on 24 inch alcoas wondering how much to narrow the rear end to make it lay frame. if anyone can help me figure it out i would love it.

if you are running all 4 24'' on the back use a single rear wheel drive out of a f250 that will save you money and shouldnt have to stretch your fenders. i never done this in a ford but it works for chevys. i can be wrong but you got to start somewhre . good luck

Can you use a cab and chassis rear end? Or will that still have to narrowed?

yes you can do that... i did it cuz i already had the srw rear end. it dont have to be narrowed unless you want to.