I have a 1998 K2500 that has just started an issue today. It has a significant vibration while decelerating. Its starts around 50mph and stops at around 25mph. Doesn't do this while accelerating. The U- joints look ok. Truck only has 135k on it. It does have a vibration between 70-80mph then it stops above 80. I don't think the 2 are related. Any help would be appreciated.

 

could be a few things. i know even a cv joint can cause vibrations only on deceleration. could be the u-joints