I've recently hydrolocked my 3.0 and my buddy is going to give me a 22r engine with tranny and a transfer case. Just wondering what all I'm going to run into doing this swap. Am I going to need a new harness and engine mounts?

 

Not a common swap,

Different mounts and depending on what 22r you're talking about the wiring is also different, the early 22r's are easy enough to wire up stand alone but 22 re's not so much and they get progressivly more complicated as they get newer into the 90's.
I don't know much about the automatics but with standards the transmission won't bolt up and the only bell I can think of that'll make it happen is a 22ret (turbo) which are not common, and then you would likely need to use the turbo trans as the input shaft is longer. Maybe some odd ball bell from a cresida or something or maybe an aftermarket adapter?
In the end it might be cheaper to yank a v6 from a wrecker or grab one from craigslist, I see them for under 300 all the time. Even a 3.4l would be easier but they're not cheap.

 

It's a 22r engine with the transfer case and transmission, so I should be able to just throw it in, and do some wiring and that's it? (And mounts)

 

Either fix the 3.0 or swap a 3.4
Like it was said before not a common swap, it would be like taking steps back from the 3.0

 

If you're looking at the engine/trans combo then your looking at mounts wiring and driveshafts, the 4 cyl and v6 are different, you can adapt the plates or just drill out the holes but that can get slopy.
4 cyl transmissions are shorter in the standards I imagine the automatics must have some similar difference. That means moving your cross member and shortening/lengthening the driveshafts probably.