I think what you're looking for is a 242. I took my 249 out and swapped in a 231, they all work. There are a couple sets of wires behind the VIC that tell it what 4WD setting you're in. Yours will have the black ones connected, seperate them and connect the red wires and you'll be all set.
As for the t-case swap, look at the write-up on jeephorizons.com and read a bunch about input shafts and gear cuts before you try to find a donor case.
93 Grand Wagoneer
5.5" Hybrid Lift/BDS CA's