There are a lot of independent garages in your area with great reviews on both google and yelp. Dealerships are known to gouge prices on both parts and labor. Labor at a dealership can be up to 2 times that of an independent shop.
R&S Automotive
http://www.rsautorepairs.com/ may not be a 4x4 shop, but if they are a plow dealer, they have to have better than a fair understanding how 4 wheel drive systems work. They also specialize in engine and transmission swaps.
From my quick google search they would be my first choice to have this issue checked out. more than likely the linkage came unhooked from either the shifter, or the transfer case. The NP231 and NP242 (the 231 was standardmand the 242 was an option) werr not known for not shifting into 4x4. They have thier problems, but shifting reliability isnt one of them.