When I let off the Throttle I feel a shutter/ Hear a shutter coming from my truck. It sounds like it is right below the driver’s seat almost like the front 4x4 shaft has a bad U joint but of course this isn’t it since it is in 2wd. I checked all the front end ball joints and U joints and everything is fine. My very rear U joint between the rear shaft and the axle needs replaced. Could this cause a shutter when I let off the throttle? Or is there something else I should look for? I also checked my rear wheel spacers to make sure they weren’t working loose but those are fine as well. I replaced the rear U bolts that connect the axle to the leaf springs in order to mount my traction bars. They don’t seem to be working loose though. What makes me think its a driveline problem is that it only happens when I let off the throttle and there isn’t pressure on the driveline. At constant throttle or acceleration it is fine. It is really bad at speeds greater than 50 mph. Thanks.