You have a couple of choices, one is easy. You can either convert the current trans you have by getting a 4WD output shaft, remove the tail housing from your trans and bolt on a tcase with adapter housing, or unbolt your trans and bolt in a 4WD trans and tcase. Find a 4WD ranger with the same wheelbase as yours and grab the driveshaft out of it and your set

I thought about doing this to my dually as I pull heavy loads in very hilly terrain...
SVT
All good except for one thing,
The Ford engines all have their own unique bolt pattern, with the exception of the 2.9L and 4.0L (those swap, and they're the only 2).
Finding a 2.3L 4x4 manual trans is near impossible, if you find one, also buy a lottery ticket. They're out there, but don't count on finding one.
x2 on the driveshaft of the same wheel base truck.
Easiest route is to pull the transmission, take it apart just enough to swap the output shafts at the back of the case, and put it back together as a 4wd model.
'92 should be into the strictly M5OD years, any year/engine M5OD transmission will work, just need the tailhousing (or 4x4 adapter housing), and rear output shaft. That should be all you need. If you're careful/smart, you'll be able to pawn off a good working 2wd transmission afterwards to help cover costs.
Use a BW1350 manual shift case (Gen I and Gen II rangers and Bronco II's), these are all over the place and can usually be had for $40-$50 apiece, sometimes less, and occasionally, free. Unlike the transmissions, it doesn't matter which engine is in front of the t-case, they're all the same. All Ranger Transfer cases will swap with one another, regardless of engine or transmission (the Explorer AWD cases are the only exception).
I used a freeze plug and gasket silicone to cover the end of the front output. It's an
internal spline even though it's a slip yoke, so you can run around all day with no front driveshaft, it's just to keep crap out of the end.
The manual T-cases are more reliable and have no electronics to wire in, or have issues with (like the shift motors).
ALSO, be sure to grab the shifter assembly and shift boot from the donor truck too.
I'm in the middle of this with mine as well as soon as I stop working double shifts. I have every intention of doing a write-up on this. It's just finding the time to actually do the swap.
It seems kind of a pain, but you're really just switching around factory parts.