I do very well with my lifted 4x2 on 35's with a rear locker. Not as good as some 4x4's, but better that some others.
I'm converting mine to a solid front axle 4x4 this spring after my profit sharing check come in. Cost is variable. If you do the work yourself, including rebuilding a salvaged axle, you can do it for around $2000.
However, you must remember that you need a different transmission, or have your transmission converted. The output shaft on the 4x4 and 4x2 transmissions is different because of the transfer case connection. On 4x2's the shaft is quite long and extends to the end of where the transfer case normally sits. On the 4x4 the shaft is considerably shorter and the transfer case occupies the space the "tail cone" takes up on the 4x2 transmission.
Pre-1998 TTB Rangers may be able to use their existing steering box for the SAS (SAS=solid axle swap), however truck like my 2002 IFS Ranger basically throw away everthing but the steering wheel and shaft because a steering box is needed to control a solid axle -- you can't do it with a rack. (People will tell you someone has -- but you wouldn't want to drive their truck for sure).
There are guys doing SAS on their Rangers all over the board. Just search on SAS and you'll find them.
Now, not many do the 4x4 conversion, but here's my reasons:
1. I like my truck.
2. I've done so many mods I don't want to start over.
3. Many of the mods are offroad oriented (like the 31 spline FX4 axle and Auburn ECTED electric locker I swapped into the rear).
4. I'm too lazy and disinclined to start all over with all the mods I've done.