I have a high speed vibration, there is nothing until about 65 and it gets even worse over 70, it is at this point undrivable at those speeds. I believe I may need to replace the whole rear drive shaft, there is what feels like some slop where the shaft slides onto the output shaft, both ujoints are tight with no slop but the weights are peeling off and the balancer looks pretty crusty.

Things I have ruled out:
All four wheel bearings are tight with no play up and down (rear does have in and out)
All four new rotors and pads, all four wheels spin free from the breaks
Front drive shaft is brand new (was blown apart when I bought it)
All bushings are tight, just had the rear lower control arms replaced under recall
All CV joints are tight and boots are good
All four tires are 5K pretty much new tires
All four new TPMS sensors and then re balanced wheels

The wheels are the only other concern, this jeep was abused a bit when I got it, some minor front end damage and peeling bedliner on the wheels, they *could* be damaged but there is no outright visible bends in the wheels at this time.

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06' Silver Limited CRD

Secondary fuel filter from wwdiesel
Northstar AGM
GDE Hot Tune
EGR delete
Suncoast TC
Transgo Kit
Carter Intank-pump
SAMCO Hoses
Silicone Intake hose
Silicone Vacuum hoses
Hayden HD Fan Clutch
ARB Front Bumper
Bosch 5V glow plugs
Gen II Fuel Head
Rockfather II Lift
GM 11 Blade fan

Have you removed the rear drive shaft to check the u joints? They can seem tight while the shaft is installed.

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2006 Jeep Liberty CRD Limited
Gen2 Fuel Head - Magnaflow Exhaust - Ram transmission swap - In-Tank Lift Pump
Moab Wheels - 245/75/R16 LR E Cooper Discoverer AT3 Tires - OME Lift 790/90009 948/60069 - Etecno Glow Plugs - V6 Airbox
RUNNING B100
Pic of my Jeep!