So I am currently shopping around for a Samurai, and I've come across a few ads one that caught my eye said that the rear end went out, and while the back breaks aren't hooked up and the suspension is gone in the back (both easy enough fixes). It also says that that the 4wd works, fine but it wont do 2wd. So my question is, what could the problem be 4wd but no 2wd? I have tried a search but cannot seem to find anything.

pulling with the front axle in 4WD

The main cause of 4wd all the time is the transfer case being "stuck" in a 4wd position.  This is usually caused by a worn out "shifter sheet" which can be replaced for less than 20 bucks and 10 minutes of "holding your mouth right".  Try a search for shifter sheet at Ack's FAQ for links to informative forum threads on the subject.

I hope that this helps!

OK, from the looks of this post, I though the rear axle was bad and the
gears were broken lol, and the suspension is gone, as in missing or weak
springs and blown shocks??? 

Wild

Well I've tinkered with one other engine, and that was on my 82 Honda Passport C70, so this is a slight step up. It apparently drives well and the engine is working fine or so I've been told. The 4wd works so I assume that it's not the rear axle or the driveshaft. I have been doing more reading online and it really seems like it is one of two things. As you mentioned it could be that transfer case brushing, or a problem with the locking hubs. The rear suspension must just need replacing, based on pictures that seem to be the case, which again isn't too much of a problem to fix.

Edit: On another note Thank You! I really appreciate all of the help and feedback. It means a lot, and while I've been lurking in the shadows as a guest for a while, this is one of the major selling points for me for buying a Sami, the community and amount of help and support out there. So again, Thank You!

Update. So some more breakthroughs. Apparently when the transfer case is put into 2wd it does not go anywhere, and when it is put into 4wd it only uses the front two tires. Again it appears that the driveshaft is fine, or so I have been told. I won't actually see it until friday when I decide if I want to buy it, so the more i can know about a potential problem the better. Any ideas what it could be? Rear Axle?

Update. So some more breakthroughs. Apparently when the transfer case is put into 2wd it does not go anywhere, and when it is put into 4wd it only uses the front two tires. Again it appears that the driveshaft is fine, or so I have been told. I won't actually see it until friday when I decide if I want to buy it, so the more i can know about a potential problem the better. Any ideas what it could be? Rear Axle?

If it is the rear axle, you should see the rear driveshaft turn if you set the t-case to 2wd.  Otherwise, the rear output on the transfer case is broken.

If this person wants more than $500 for the Samurai, you should tell him to pound sand.  Then offer him $250.

Or maybe stand him in front of a trap and trigger it.  He could keep the extra-normal critters inside company for a while. 

Well that makes sense. So based on what I've learned since yesterday. It really can one one of several things, they are as follows:

If the driveshaft doesn't turn:
The problem is the T-case rear output. My question is, does one need to replace the transfer case? Or can one simply replace the transfer case output shaft (what is the difference in the output shafts in regards to front/rear?)

If the driveshaft does turn:
The problem is either one of two things. One of the rear axles is broken and there is no locker. Or, the rear transfer case broke and needs replacement, which is what I believe it would be. If this is the case, to be able to drive the vehicle the 250 or so miles back from where I could potentially be purchasing it I would remove the rear driveshaft (I have to drive in 4wd as 2wd doesn't work) so it doesn't stand the chance of accidentally catching on something and damaging more in the rear axle.

Does any of this sound logical? Also I've been told that to take the rear driveshaft off I would need a 12mm wrench?

I thought it was a 14mm wrench, but bring two of each just to be sure.  Since it uses a flange  you can pull the drive shaft and idle it home.