All samurais have 3.73 (3.727 actually) diff gears.
You can use a front third in the rear, but....
you will have to change out the sidegears....fronts are 22 spline, rears are 26 spline.
some front carriers are 3 pin (or 4 pin, depending on who you ask), and some are 1 pin (or 2 pin, again depending on who you ask). All rear carriers are 3 pin (4 pin). So you want to make sure the one you are swapping in is a 3 pin/4 pin carrier.
With any third you plan on swapping, make sure you compare the pinion flanges...some are small bolt pattern, some are large. You can redrill the large with the small pattern, but I don't recommend drilling the small for the large pattern.