Mechanic can't find issue- checked bushings, shocks, etc. 2012 high top gmc Savana conversion van (explorer) AWD. When HEAVY acceleration in reverse only you can hear a popping noise (sounds like a creak or spring sound). The car has 24k mikes.

Modern repair shop should have the proper equipment to diagnose .. *Chassis ear* is a device that monitors noises as vehicle is being operated .. Drive on lift with suspension jacks is also a useful piece of equipment - vehicle can be operated while qualified personnel listens for noise when chassis is at normal ride height - plus *knowledgeable* hands-on inspection is essential.