I have a 2004' Dodge Ram 2500 diesel 6sp manual, quad cab with 140,000 miles. Suddenly the 4-wheel drive will not disengage. Yes, the lever works fine, but the front end remains locked up. Any thoughts on what this might be before something binds up on dry ground and destroys something?
What can I test, or what and how can I check? Thanks!

 

I've read that the bushings and linkage is suspect to wear/breaking/bending... I'd make sure that the right things are happening under the truck as the shifter is showing.