Mmmmmmmmmmm.
I threw a 4x2 power steering kit in the bin last August.
I threw a Pathfinder steering box in the bin last month.
Twice now I've regretted not stripping and storing them, but then again if I had nobody would need one.
Let's have a look on FAST...
The 4x2 and 4x4 power steering boxes have the same part number. Compatible. Sorry for throwing mine in the bin.
Now, 1996, you'd have a KA24E, yes? Surprised they still fit armstrong steering to them in 1996...
As best I can tell, the pump assembly doesn't change with engine or 4x4/4x2, so you can get one of those from anywhere. However, mounting bracketry varies greatly and I can't really tell if the brackets from a Z24 are compatible with those from a KA24E, they look like a similar mounting pattern but I don't know about interference, so you'll have to trust Pinelli that the bracketry between Z24 and KA24E are relatively compatible.
All other relevant parts are universal.
Now, my favourite part: Parts which are also D22 compatible -
KA24E mounting bracketry
Power steering pump
Universal parts (reservoir, piping)
The steering box looks like it might work with some massaging - different part number, but not indicative that it won't fit.
So that broadens your search. I wouldn't bother with aftermarket when Nissan already made a million perfectly good units.
Go and harass some wreckers, or keep working on those pectorials till a kit comes up on eBay. It happens.