Simple test: Place transmission in neutral with parking brake on good and tight, get under vehicle and insert a medium size screwdriver into rear U-Joint and rock drive shaft back and forth (forward and reverse) and look at what moves on all suspension items connected to rear axle and what does not move. Any excess movement or play in any of the suspension parts should be found very quickly...
Note: this test can also be done while vehicle is on a service rack while lifted!
_________________
Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve