i have a 07 level 2 (has 33's on it if this will count) with around 260kms (161 miles) on it. starting this winter, i have noticed a cluck or thud when the truck is in 4x4. it feels like its from the front end, or front side of the truck, and not the back. the other problem is its intermittent. it will happen when being driven a distance of around one km, or around a 1/2 mile no matter what speed. also the faster you are travelling, the harder the clunk or thud. the best way i can describe it is it feels like hitting a joining point on the road that is separated. it will only do it in 4x4 and not 2wd. the front u joint was replace around 2 years ago, as well as the passengers front cv axle. the drives axle was also replaced in the spring if i remember right, or last year. there is no grind sound, and its not popping out of 4x4 either.
thanks in advance.

 

All 4 tires are 33's and all the same air pressure(about)?

What you describe is like something is binding up then releasing
Only in 4WD would indicate transfer case chain drive at output shaft connection or front axle, I know doesn't narrow it down much, lol

Are you on loose surfaces in 4WD?
This lessen the chance of binding up as wheels/tires can slip a bit

You could drop the rear drive shaft and drive around in 4WD to see if you still have the "clunk/thud"
This would narrow it down to front axle binding up when powered, not transfer case

 

its on mixed surface. snow covered, ice covered, and bare.
im not really wanting to pull the rear driveshaft out and drive on the front axle, thats too much stress on the front end parts with 33's