vibration and clunk noises, not driveshafts

bm2004x

Test Drive
Location
United States
I have had this for a while on and off but now more apparent.


first, when I am driving thruway speeds and let off completely, nothing. same speeds and slowly decelerate or 95% let off and still have some pressure on pedal, I get a rattle like a pinion bearing problem. - I don't have any leaks in the rear end and new u joints fluid and shaft looks perfect. no play in that bearing from what i can tell standing still.

Second issue that is related; when at thruway speeds, or anything above 25 mph, I let off the gas and then reapply gas, I get a clunk. If i apply pressure extremely slow and steady, I may not get the clunk. no debris when i changed rear end fluid or tc fluids. could the pre-load on the pinion change by itself? would pinion bearing fail or be failing with no leaks?

info about my truck
2004 xterra v6 auto
3" leaf lift with stock shackles
175,000 miles. all new fluids and well taken care of
33" tires that are tight, no loose bolts to make the noise.
original motor mounts and drive line mounts
 
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