2012 Limited 4x4 Dually Front Drive Shaft

[Michael J McGinn]

I recently discovered the greasing requirement for the U joint. I've read through a bunch of threads concerning the ability to rotate the drive shaft by hand with the vehicle in park. My drive shaft will not rotate by hand. Should it on a 2012? It's in 2WD. Seems to drive fine although I get an intermittent "service 4wd" warning on occasion. It comes and goes. I don't use 4wd as I haven't had the need in a long time. Sitting parked, I have shifted it from 2wd to 4wd and it seems to work. Blinking yellow light during the transfer followed by a solid yellow light. I believe that's normal.

Just wondering why my drive shaft doesn't rotate freely when everyone else seems to. Is there something unique with a 2012?

Thanks
Mike