I never had any issues (or noises) going from 2HI ---> 4HI or the opposite on the highway.

I was doing around the speed limit.

I know and hence why I was putting it back in 2wd, the side roads were snow covered but the highways were fine. And believe me, I'm with you on the 4X4 doesn't help stop or steer. My car only runs on snow/winter tires in from dec to early march and the difference is night and day, even compared with good all season. And actually I'm needing new front tires for my Jeep now so I've had to be extra cautious when the white fluffy stuff is falling. And tomorrow they're calling for up to 5inches...you'd think people have never seen snow the way most of them drive around here.

your front tires being more worn than the rear may make the front and rear spin at different speeds

I've shifted on the fly up to 40MPH and no problems, and have the NP242. This means that I go 2WD>4PART TIME>4 FULL TIME with no issues.

Hmm never thought of that. Maybe I'll just have to swing for 4 new ones.

I've been thinking about this... What is the danger of engaging 4WD on the fly while the wheels are turned? I have a pretty wicked driveway and engaging 4WD while turning would be useful. However, if it has the potential of damaging something then I won't do it.

I'm not sure either. I do know it'd be pretty bad if your wheels were turning at different speeds (front and rear), as you'd be snapping your front end into motion abruptly.

I did it once and it did a grinding noise, so I left it in 2wd. Mind you I was in a parking going 10-15MPH so It probably didn't do much damages. But, I haven't done it since....

P.S.: Don't do it

should be fine as long as the surface is slippery enough to allow some wheel slippage so the components don't bind

Then engaging 4 while the wheels are turned will yeild the same result as trying to turn while already in 4. Excessive U joint and tire wear will be the main issues.

My jeep did the same thing when I first got it but it woried me so much i looked at all the components every time i used 4hi and my cure was just while in neutral stopped to pop it in and out of 2hi 4hi N 4lo and back multiple times, and now it shifts so smooth I can shift it at almost any speed and no noise is noticed except the usual t-case shift lever vibration. the best part is that it shifts out of 4x4 almost instantly. but thats just my experience. lol

in a 40 mile trex to work i shifted back an forth from 4 hi to 2 hi at least 20 times....id rather do that then run 4wd on the bare parts of the road....an like said above i only do like 35 45 any ways so you will be fine