2008 957 Clank/ratcheting sound on harder accelration
 

My 2008 with 160k miles has started developing these clicking/ratcheting sounds on harder acceleration. Mostly when starting from stationary, but also sometimes during slower driving and accelerating to faster.

Assuming its some sort of torque related issue? Sounds like it is coming from the center of the car, maybe towards the passenger side?

Hard to explain the sound but could almost sound like a ratchet strap getting tightened down.

I have replaced the cardan shaft on this car.

Any guesses on where to start? Could it be the stepper motor? I know I had issues with that on a previous car. But symptoms for that was a little rough gear changes.