When I was picking an axle for my 58, I found the rims that I wanted, picked a tire the height I wanted that fit them, then worked backwards from there to the axle.
You need to take into account several pieces to answer that question.
The axle width (usually measured WMS-WMS) to see where the rims will be located.
The rim width/backspacing (to see where the inner and outer edge of the rim will be).
The tire width relative to the rim width (to see how much the tires will extend past the rims).
Are you planning to raise or lower the truck? If so, that will affect what tires can fit as well.
Do you know what kind/size of rims you want?
When I was picking an axle for my 58, I found the rims that I wanted, picked a tire the height I wanted that fit them, then worked backwards from there to the axle.
I have seen the axle from a 2004 Suburban put under a 59 with the stock (Suburban) rims/tires and that is just about the max outside width that will fit. I don't recall the measurements on that though.
With a little more information on your plans/goals, we can give you some better guidance.
all of the above starting with what look do you want aka rims and tires. then you will know your rim to hub spacing then you will know where your backing plates will be etc. then its get out the ruler.
example my 56 has a colorado rear end under it. not just any colorado rear end because even withing the same year there were 3 different widths.
