I have an 89 with a 4.0 auto, and 242 transfer case. When I put the truck in 4H full time and accelerate its smooth but when I let off the throttle I get a bad vibration. Does not vibrate in part time. Also it takes a long time for the full time to engage and hard to disengage 4wd any mode except 4L. Any ideas on what causing this vibration. Also anybody have a good write-up on transfer case linkage adjustments?? Thanks