It'd be great to have a little more information. Is it the electric shift 4x4 or on the floor shift 4x4? I've heard of the solenoid going bad on the electric, while on the floor shift they sometimes just won't engage because they haven't been used in so long, which could definitely be your problem with it sitting for 2+ years. Make sure nothing is binding underneath, and see if anything needs to be lubed up...there have been many other posts on this subject.
Another good place to start would be draining the transfer case. Easy to do...all you need is a 10mm to take off the crossmember, then pull the drain plug. To fill, its easiest to use a syringe to suck up the tranny fluid (you will use 2 quarts of regular Mercon, however I am told you can also use Mercon V in it as well) and squirt it into the top fill. Its just in an awkward spot, you can't really get a funnel up there. It took me all of 20 minutes from start to finish doing mine. The fresh fluid in there might be good for it...mine was being crabby going into 4 Low, after the fluid change and a few miles under the belt, she seems to be clicking right in.
Last edited by JRV; 02-17-2009 at 06:09 PM.