Driving to work this morning and all of a sudden my 2005 stops forward motion and I hear and feel a terrier grinding noise. Read some threads on mud and push Center Diff lock on dash and that seems to make it so I can drive to mechanics. When I arrive and disengage CDL truck seems fine. Mechanic tells me to take around block and it still seems fine. About 20 mins later problem returns and I was able to once again fix it with CDL button and limp to mechanics shop. Some real time help here would be great as mechanic who is awesome is booked a couple weeks out.