J20 steering box
 

Why?

Why swap in a J20 steering box?

The larger piston has some use, but the variable ratio is IMHO not an upgrade. It also has the wrong mount style (4 bolts) also.

It will take the same power steering lines, or at least the fittings are the same, you may have to tweak them for routing. Edit, only if it's post-80, pre-80 stuff uses different fittings and I would not touch it. The input shaft is larger, but you can get the adapter off a newer Dodge truck.

They're also expensive and harder to come by, or at least they seem to be to me, I own a few FSJs and I do not find their parts to be plentiful or cheap anymore.

If you want a big piston 4 bolt mount steering box a 94+ Dodge Ram 2500/3500 is a much easier to source.

Still, with the low price of hydro assist, and the much greater upgrade it provides, I wouldn't likely bother. Unless you're really opposed to running hydro assist.

The Durango box is at least pretty much a bolt in.

Most of the small Saginaw boxes are pretty much the same, I'd assume the S10 one is likely very similar to the XJ one and not much (if any) sort of an upgrade, but I have no personal experience with it.

What issues are you having with your power steering? You could easily be suffering from a worn or poorly adjusted pump rather than the box not being large enough. Or your scrub radius is incorrect and you would be better off addressing that than changing the box.

Worn out as in sloppy? Or leaking?

The slop can be adjusted out. There's seal/bearing kits out there too, but it can be a bit annoying to get the right ones.

Upgrading things just for the sake of it is a great way to open cans of worms that you don't need to open. Especially if you're buying reman parts to do it. The chances of actually getting the correct WJ pump as a reman are low, they will often just throw whatever in the box because 98% of people won't know the difference and the casting marks are almost exactly the same. It also isn't an upgrade unless you NEED the increased flow, which you do not need with a conventional steering system; being that a high flow pump on a low flow system does nothing but increase heat and turbulence in the fluid, which is asking for reduced life and increased noise. I run a WJ pump and it's great for hydro assist, but I do not think it will likely last long without the constant load/flow of the cooling fan, the reservoir is even designed with the constant flow in mind as the return port from the fan is shaped to serve as an ejector pump to improve scavenge and reduce turbulence (turbulence = cavitation).

If you want a bit more jam out of the steering I'd adjust the pressure regulator a bit. And I'd only do it if I was actually getting into situations where I was running out of assist on the steering.