I've seen some other similar issues, but all include some kind of noise... I have a 2011 with manual transfer case(floor shifted.) Issue is sometimes it will work when I attempt to switch into 4hi or 4low, when it works dash lights normally, and it operates as it always has. Sometimes when I go to shift the lever feels normal but it wont engage at all, or I will have to give the lever a wiggle to engage, but often it wont engage at all. Could my issue just be that the linkage connector is worn? When I get under the truck and grab it I dont feel any play, but I have noticed the original part has been superseded by a newer part number in gm parts. Full disclosure, I haven't changed trans, transfer case, or diff fluids since about 90k miles and I'm at 150+/- k, about 10k overdue, could that be the issue? Any help is greatly appreciated!