I did look through the forum but couldn't find anything specific about this.

 My front diff has a strange problem. 99% of the time it works fine in 4x4 but occasionally out of the blue it will start to shudder. The first time it happened I thought it was the lugs from my mud tires rubbing in the wheel well on a sharp slow turn. It's pretty much exactly the same feeling. I've also notice it never does it under power going up hill or pulling. Only going down hill or in a parking lot going very slow.
Diffs are 5:13's with a 2" drop bracket, manual hubs.
Whenever it happens I just take it our of 4x4 and unlock the hubs then the truck works fine.

Maybe the air actuator not engaging??
something with the CV.

Does this sound familiar to anyone?

Sounds like it could be transmission wind-up.  Does it happen on good-grip surface when turning?

Never use 4WD other than on loose surface - when you corner, the front wheels go faster than the back, and the truck has no center diff, so the wheels have to slip to prevent the transmission "winding-up".  On a good-grip surface, they have a lot of problem doing that, but when they do, they make a lot of noise and vibration - and break Transfer Case internals!

THanks for the info. It's only happened in snow or on dirt. I'm putting an XL7 diff in the front and getting rid of all the air actuator junk and going old school. Hopefully that will help solve the problem.

I think I've narrowed down the problem. We've had a LOT of snow up here in the last week and i've been in FWD pretty much everyday and I'm noticing the shuddering is happening on tight turns when the wheel is cranked all the way or close to it. I'm guessing that is due to binding and my lift up front.

Sounds likely if the snow is dry and firm.  Here in UK, we mostly get wet, slushy snow, and it's not a problem.

Sounds like binding to me. How do AWD (subaru) vehicles deal with this? Do they have some kind of center diff? When I drive in 4WD on pavement, I take mine out of 4WD in tight turns - in my 1st Gen Kick I can shift back and forith between 4WD Hi Range and 2WD on-the-fly. Most t-cases will allow this on-the-fly shifting.

I'm sure my 2.5 inch lift and wheel spacers don't help the problem. My truck only started doing this after I put wheel spacers on. I'm guessing it's cause I now have that extra inch of turning radius.

Imho it won't be the lift (it slightly reduces the track), but the spacers would certainly magnify the effect.