My 2002 F250 7.3L 4x4 just recently started this random 4x4 engagement. About 2 months ago while driving, I noticed a vibration right under the drivers side floor board. It would come and go.. I am almost positive its the front drive axle coming from the Transfer case just randomly engaging and turning. I maybe wrong but just the other day I had the 4x4 engage out of no where on me. I was going about 70 mph going into a turn in the road when the front end starting wandering and shaking. I stopped thinking I broke something, but nothing.

I continued driving home and almost every other turn, the 4x4 would engage. Both front hubs are in auto and the switch is off. When the 4x4 engages, there isn't any lights on the dash or nothing. It's random and dangerous. I also noticed a grinding noise coming from the front end as if something is ready to break.

I also was able to turn the front drive shaft by hand to see if it was locked in. When I turned it, I noticed only one side of the front axle was turning where the front U joints are.

Does anyone have any input of where to start or what to look for. This one has me stumped and I really don't want to drive it anymore until its fixed. Something is wrong and I think ready to break.