On my 05 SE X, When I put it into 4WD, I dont hear a clunk like I used to on my old Bronco. I cant feel it pulling any differently either. Yes the indicator LCD lights up for 4WD high, and I dont slip, but I got used to the clunk in the Bronco when I hit the 4WD button.

Is it instead, 4 wheel limited slip? or is it that this it the state of the technology that were at now?

Also, there is no mention in the manual for disengaging the 4WD, other than, to turn the switch to 2WD. They dont say that you have to back up for 10 feet, and listen for a click to disengage the hubs, like I had to do on the Bronco.

Any thoughts would be appreciated.

Thanks!

My 04 is manually engaged and has the locking hubs
Just guessing the new style probably has the electric engaged solenoid or motor driven that will not be noticed very easily, and if they are like most 4X4s you will get stuck with only the right rear and left front spinning...........

Well, on my 94 Bronco, I had the electric engage button as well. 2 tires drove normally and they would switch left & right when the default drive wheel spins. Same with the 05 X 4X4. I tried it out this morning. (nasty snowstorm here in NY overnight. It works exactly like the Bronco did, but when the Bronco engaged, there was a noticable clunk.