Need new lifters
Could be a bad ball joint
Bass
sounds like cv joints
Maybe that thumping noise is the sound of another car smashing into the rear of your car.
The driveshaft might be out of balance or dented in some way, also check the u joints
Bad tire? Rotate and see if thumping changes
The frist thing I would check would be the engine mounts.
worn torsen differential
Have that tire checked sometimes the belts inside can break and cause a thumping noise
Check your Brakes or have someone look at them.
water/friction
A thumping noise under a van can be caused by several issues, including a loose or damaged exhaust system, worn-out suspension components, or a failing drive shaft. It could also be a sign of debris caught in the undercarriage or an issue with the tires, such as uneven wear or a broken belt. If the noise persists, it's advisable to have a mechanic inspect the vehicle to identify and resolve the underlying problem.