If it is the strut rod bushings, you can feel and hear the clunk by tapping the brake while the car is rolling slowly. The tapping cause the front wheels to lock up while the body is try to push forward. The wheels then push the strut rods against the body causing the noise. If someone is watching from outside, he could see the front wheels move backward relative to the body while braking. Either way, Phill, the flex disc should be inspected regularly.
Good luck and have a nice trip.