vmk

Getting a single clunk every time the brake pedal is pressed while in PARK, with the vehicle running or in the ON position.

Don't hear it when the vehicle is in Drive or Reverse.

I tried feeling the brake calipers to see if one of the pads was loose and not seated properly but don't feel any vibration.

It's coming from front-middle of the vehicle. Could it be the Brake booster or master cylinder?

MP4.2+6.0

By chance are you just talking about the shift lock that only allows it to be moved from Park when you have your foot on the brake?

vmk

I never thought of that. Yes it could be that. is it supposed to be that loud? I can feel the vibration in the shift stick and it can be heard from the outside too.

MP4.2+6.0

this may have been superseded to something electronic too (rather than the earlier solenoid systems that locked out the shifter action), but maybe look into it a bit.

snapdragon

It sounds like the P lock as said, but mine is barely perceptable, unless the radio and vent fans are off and I concentrate on it, so it sounds like yours is louder.

FlyTyinFool

That was my first guess to.

I notice mine a lot more, now that the car is over 100K miles. I never really noticed it when mileage was between 60K to 80K miles.

My 2 cents...