1993 Jeep Cherokee computer compatibility

I've changed my Jeep Cherokee form2by4, to 4by4.I need a computer.Can I use the original 2by4 computer,or must I change to the 4by4 computer?My computer is on the inside fender well on the drivers side.I've found most others to be under the dashboard.Are they the same? Do I have to change the wire harness for the 4by4 computer.This is all very confusing.