2000 TJ 4.0 /auto - bone stock except for 31" rubber.
For the last few days my steering has felt like I was in 4wd.  The dash indicator is not on and the shift lever is in 2H but the front end is grabing when I turn corners just like when you are in 4wd on dry pavement.
I don't think it's the transfer case because I can spin the back tires on wet pavement.  I have shifted thru 2H-4H-N-4L and back but it didn't make any difference.  I also hear a rotating noise of some sort from under or near the drivers feet.
Please help!  I keep having visions of exploding differentials!  Not good.  Not good at all.  

      Check the front axle U-joints, at the steering knuckles. Sounds like they may be worn out and binding. As long as your under there you should check your drive shafts too.  

How do I check those?  

jack up the tire, and move it around by hand  

Everything in the front end is tight.
With the engine off I put the trans in neutral and had my daughter shift the t-case thru its gears so I could watch the linkage.  Everything was moving fine.  I took it for a test drive and the front end bucking was gone.  Everything was smooth again.  So I either have a linkage problem or an internal t-case problem what worked themselves out by shifting the t-case with the engine off.   

        Jack the front of the Jeep up, in 2WD, turn the wheels left or right to full lock. Rotate your front tires by hand and see if you feel any binding. Should spin very free. You can look at the joint, and even pry on them, and they can feel tight, but they can still bind when the roller bearing rust and swell up. While your doing this, keep an eye on the other side. If you feel it bind and the other front tire wants to turn the same way as the one you are turning, you may want to pull your diff cover and see if you have stripped a tooth off a gear. With the open diff, the other tire should turn in reverse, of the one you are turning, smoothly, all so with no binding.  

I turned them like you described but I only did one wheel at a time.  Both turned freely.  The only noise was from the brake pad rubbing the rotor.  I will do it again this evening with both wheels off the ground.

A guy from another board suggested doing it with the t-case in 4wd so that there would be resistance.  Didn't make sense to me.  Any thoughts?

          I know what hes getting at. If you don't feel it in 2wd, lock it in 4wd and do it again. This will lock the drive shaft, and force the diff to rotate. If you feel it then, something in the axle let go. Not having a disconnect in you front axle, your front drive shaft is always turning when you drive, even in 2wd. You should still check the joints in your front drive shaft.  

I put it in 4H this morning and I could hear and feel it engage.  I drove it a couple block and put it back into 2H.  On the very next turn the front end was bucking like it was still in 4wd.

I went home and did the following:
#1:
Engine Off
Trans in neutral
T-case in 2H
Both fron wheels off the ground
Turn either wheel and it is the only one that moves.  The other wheel does nothing.  I forgot to look for driveshaft movement. 

#2:
Engine Off
Trans in neutral
T-case in 4H
Both fron wheels off the ground
Turn either wheel and the other wheel turns in the opposite direction.  Front drive shaft does not turn.  Shouldn't the front shaft turn if the T-case is in 4H?  Maybe not because the trans was in neutral?  I don't know.

Put it back in 2H and took it for a drive.  The front end still bucks on cormers like its in 4wd.

I really hate to take it to the dealer because I know they will rape me but I don't want to just throw parts at it either.  Someone please help! 

       Are you turning the front wheels all the way left or right before you spin the tire? Very important to feel if the U-joints are binding! Try it both ways, left and right, and look at the joint while you spin the tire. Spin it slow, should be smooth like butter. The weight of the tire may hide it some. Pull the tires and spin the brake rotors the same way, you. You may be able to feel it better. Another thing you can try, remove the front drive shaft and take it for a ride and see what you get then. If its still doing it, its in the front axle, if not your T-case is the problem, but not likely. Still sounds like those axle joints, one or both. I must replace mine every two years or so, because of water crossings, and all the road salt that gets tossed around hear. They get rusty and tight inside. This in turn pulls at the steering wheel, because they don't want to bend. If they were loose and sloppy you may not feel it.  

I have turned the wheel to lock in both directions with the tires on and off.  The joints are smooth.  No noise whatsoever.  After jacking it up last night and spinning the wheels and running the t-case thru it's gears the problem went completely and totally away.  Bad u-joints don't fix themselves.  I am thinking t-case linkage or the t-case itself.

Comments - ideas?

Did you do what Twitch said?  If its broke take it to the dealer or an off road shop.  An investment like that will probably cost you less than a major off road tow bill when you front driveshaft looks like Hiroshima.