Very difficult to shift 4x4
If the shifter does not move easily, check the linkage for binding. (get under it and look while some one moves it). For most other issue, check this out, http://www.dodgeram.org/tech/repair/..._engagment.htm
if there is no linkage problem, and it requires superman strength to shift - there is something wrong with the shifter or the tcase.
try turning ignition off to shift. or shift transmission to neutral. see if either of those help.
try turning ignition off to shift. or shift transmission to neutral. see if either of those help.



