Right, purchased myself some pro ramps for Christmas to give myself some more wiggle room when working under the green beast. Got under there today and proceeded to spray my CDL linkage with a can of PB Blaster. After some wriggling in the cab and under the truck with a pry bar I still couldn't get the Linkage to shift, I did however remove the pin before the CDL switcher and was able to engage it (light on the dash at least, didn't test drive). I'll keep working on the linkage but I'll test the CDL using the manual method for now when I hit the trails this weekend. At least it looks like I have a working diff lock!