Goes in high just fine. Use it in and out in alaska a bunch.  Hardly ever use 4 low now for several years . I know to back up neutral  etc it just will not go in and and sometimes makes a just awful noise    So what is the problem??

Is the shaft linkage adjusted enough to allow the shift properly?

I had a similar issue, the  ball and spring on the rooster comb was tangled up.  you can see the issue in the Transfer case rebuild article.   you can see me holding the spring after removal with plyers.

 

 

 

 

 

Great info thank you.  But way out of my expertise to repair for sure.  Would need to go to transmission shop.  Wonder

 why that spring gets  tweaked out like that.  Probably only used 4 low a half dozen times when truck was new

If you dont use it you lose it! They are not bad to re-build at all. Fairly simple and cheap honestly, maybe take a day at most.

A 7800 lbs truck with a 300 hp Cummins in 4 high will  pull anything 

you ever wanted.  No need 4 low.  So what would a transmission shop charge me to take it out and fix it.  If they will even work on my truck ?

Shouldn't take too much being the transfer case is easy to remove. Two driveshafts and 6 nuts around the transfer case.