Agreed,shouldn't be too hard to pinpoint, especially if you have Chassis Ears as HT mentioned.
Check into these TSB's, may apply to your concern
Subject: Noise Or Clunk In The Rear Suspension - keywords bushing clunk noise rattle rear suspension thump #PIT3323C - (01/23/2007)
Models: 2005-2007 Buick Terraza 2005-2007 Chevrolet Uplander 2005-2007 Pontiac SV6 2005-2007 Saturn Relay
This PI was superseded to update Model Years. Please discard PIT3323B.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI. Condition/Concern:
Customers may report loud clunk or noise while driving in the rear suspension of their crossover sport Van equipped with FE1, FE2 or FE3 rear suspension. The noise maybe described as the muffler hitting the floor pan or a loud slapping noise. Recommendation/Instructions:
Inspect and replace the rear trailing arm bushing P/N 10341351 as needed.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
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Subject: Stiff Rear Upper Suspension Or Shocks Clunk Over Bumps - keywords bushing cargo GMT201 noise rear #PIT3861A - (08/04/2006)
Models: 2005-2007 Buick Terraza 2005-2007 Chevrolet Uplander 2005-2007 Pontiac SV6 2005-2007 Saturn Relay Cargo or Incomplete Mobility Vehicles Only
This PI was created to add 07 MY. Please discard PIT3861.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI. Condition/Concern:
If the customer/fleet operator finds the suspension too hard (shocks clunk because of full extension over bumps), ask how the van will be used. If it will be loaded with several hundred pounds, the suspension will be alright. If it will be used predominately with light loads and the customer is objecting to the ride characteristics see recommendations below. Recommendation/Instructions:
Replace the rear springs with 22132418 which will reduce the spring preload by 600 pounds
- Make sure the customer is objecting to the ride characteristics, not the dealer sales department.
- Record trim heights with the original and the replacement springs and forward the information to tom.geist@gm.com.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
