Hey guys, new here. I've been having this issue for a while now and haven't had much luck finding an answer. I noticed sometime last year that when I switch to 4 hi with my 2006 auto 4l it works but will make a loud clunk pretty often and kick out of 4x4. It's pretty easy to tell because I'll have good traction in snow then *CLUNK* and the rear ends fishtailing. It seems to re-engage after a second or two. It's had issues in the past with the motor on the t-case. Was replaced in 2015 but I'm suspecting it's bad again. this problem also happens in 4 Low but not as often. Any ideas are welcome, Thanks for the help guys!

 

Maybe the actuator!! I'm looking ito it too. I have a 1995 ranger 4.0 xlt. When I put it into 4high ihear some grinding, than back to 2wd it sticks than finally comes out of 4wd.

 

It seems to be a pretty common problem, my trucks pretty rusted out and I'm not trying to put all kinds of money into it, that's why I'm trying to find out exactly whats going on rather than trial by error. I've had some issues with it not wanting to shift into 4x4 and back out as well. I have a slow front axle seal leak as well, but i don't see how low diff fluid could cause the problem I'm having.