I have 1 of each....I have a lowered 1992 2WD, a Lifted 1994 4x4, and an ALL STOCK (and staying that way, according to my wife) 1998 Mountaineer AWD.
To swap the 4x4 to 2WD, you will need the 2WD I-beams (obviously), the Radius Arms, and the I-beam mount on the passenger side of the Engine Crossmember. That one holds the Drivers Side Beam. The other mount is the same for 2WD & 4WD.
After you get the front suspension mounted up it's just a matter of getting the transmission sorted out. You can keep the 4WD transmission and transfercase.... and just keep the TC in 2HI all the time...and never mess with it, you won't break the chain, as it is not driving anything....OR you can swap to a 2WD transmission. The 2WD transmissions are harder to find, though not impossible.
Ryan