I have a dodge 1500 quad cab p/u truck with 4wd- I have noticed more than what I was used to noise while in 4wd. It's got 170k miles with a 360 magnum and a limited slip rear. I checked all my u-joints and found one bad wheel bearing but still have the noise. It's pretty consistent and increases in pitch as speed increases- worst is at 55 mph. I also noticed it is a bit more difficult to get in and out of 4wd and I can no longer shift into 4wd hi on the fly, and when I shift out it takes a while for the case to shift out. I wish I could determine if it is coming from my transfer case or front axle. I was thinking of piping some engine vacuum to the split axle locking actuator( who ever thought of that device anyway?) separate of shifting the case - anyone have some experience this way?