Transmission Issues (I think)

I was out driving my 48 willys tonight and had some issues.  I was driving in 2WD and the clutch began to feel funny when I pushed it in.  I stopped at a light and when it turned green I shifted into first and went to go and the car just wouldn't go.  I pulled to the side of the road and tried to shift into second, third, and even reverse.  The vehicle would move slowly forward but would not really drive.  I moved slowly to a parking lot to figure out what to do.  I locked the hubs put her in 4WD and it drove fine.  When I got home I put it back in 2WD and the same thing happened the car wouldn't drive in 2WD but drives fine in $wd.  I have never done much work on transmissions or anything of that nature so I need help diagnosing/repairing the problem.  Thanks for any help.  Hope I'm not reposting anything I looked and couldn't find anything on this subject.  

It didn't really make any strange noises.  Basically it made the same noises as usual just wouldn't drive.  It will drive in both 4 wheel high and low I think but it wont drive in either 2 wheel high or low.  I'm near Fort Carson would love someone who knows a little more about this stuff to take a look.  Shoot me an email at thorschanck@gmail.com  and we could set up a place to meet if you are near me.  I'm free all weekend if you have any time.

I put it in 2 wheel low to see how it worked since I just bought the Jeep.  I'm not sure what the interlock is though.  I will jack up the rear and see what it loos like.  I take it that I want both wheels to turn when I move one of the wheels.  

Ill check it out tomorrow morning to see what happens.

So just a quick clarification on checking the rear axle.  Do I need to have both rear wheels off the ground to be able to check to see if the axle shaft is broken.  Also small update on what I have checked.  I popped the rear caps off the to see if the keys sheared off.  I put the car in gear and tried to drive it.  The car moved slightly and the rear end bobbed a little but it would not drive.  Don't know if this helps further understand or not.  

So I just went out and jacked up the back end and tried spinning the wheels with the jeep in gear.  Both wheels will spin freely with the vehicle in gear.  I take it that if this is the case I have broken the axle shaft.  I was looking over a rear axle assembly diagram online and it looks like there are two axle shafts one on either side of the differential.  If both wheels are spinning freely does this mean I need to replace both?

I had one side jacked up at a time.  There was no movement in the opposite wheel that I could notice.  There didn't seem to be any movement up, down, or side to side.  If I have time later on today I might try opening up the differential.  It seems like taking a look inside might give me a better idea of what is going on.  

Yep. That's what I would do next, pull the axles. On the way in you may find a sheared hub key. You'll need the proper puller to get the rear hubs off of the axles. Search "hub puller" and you should find plenty of discussion and pictures. This is one case where only the right tool will do. I've heard that some auto parts stores will loan or rent you one, but I don't know, I have my own. Just got done using it, in fact.

Now, turn one wheel at a time and see if the spider gear in the diff turns. You have probably twisted one of the shafts off. This happens when full low range torque is applied to the rear axle in 2wd. Someone must have removed the interlock from your transfer case that prevents 2wd low.
When you find the broken shaft, the next fun is getting the differential end out of the axle housing.