So, I took the truck to the local 4x4 specialists and had them go through everything step by step. Given the truck is 13 years old we took nothing for granted. I simply don't have the time to go through it myself. Here is the breakdown.

First checked the hubs for proper operation. Found the auto lock and lock positions work perfectly. Checked the drive lines for any, even minimal binding. Determined that one joint on the front axle was binding. Inspected all the joints and I have several that are showing signs of rust coming out of the caps. Replaced the front joint as you could feel it bind even up on the rack. Replacing it did not solve the heavy shaking in 4x4. Ran the truck up on the lift in 4x4 and it is smooth.

Had them pull both diff covers and inspect, as at a minimum figured it was original 12-13 year old fluid that propably should be changed anyhow. Both front and rear diffs are 3.73 gears. Rear diff has a very minimal chip in one tooth, but nothing that would affect operation. All the operations of both front and rear are good and do not hang up. Replaced fluid and that brings us to the transfer case. It will be installed Wednesday and while everything is out a couple more u-joints that are showing rust coming from the caps will be done as well.

So major problem is the transfer case. Surprised at such a low mileage, but also do not know the history for the last 12 years. When finished on Wednesday all the fluids in everything driveline will be changed and all, even questionable looking u-joint will have been replaced. Should get me another 12-15 years. I hope

 

let us know how it drives after they get it all changed....

 

Thanks for the follow up.

 

 

Did they say what is wrong with the transfer case?

 

Final update. I got the truck back on Friday night. From looking over the paperwork, pretty much all the u-joints have been replaced, front and rear diffs have new fluid, new transfer case and fluid and a complete 4 wheel alignment. Driving it is very smooth. Prior to the work if you were going over 15 mph the truck (electronic shift) did not want to drop into 4x4 high. Now it drops in like a warm knife through butter. I have driven it on dry pavement and it is smooth. On gravel (no snow yet) 4x4 works excellent. So I figure I should be good for another 15 or so years (I only drive about 7-9k a year)

Thanks for everyones input

 

Wonder if it was damaged somehow or if someone just used it extremely hard and didn't do any maintenance. Good to hear it got cleared up.