For about the last year, I've had a bang/thud sound happen in the front end when I backup, as well as very occasionally when I take a tight turn at slow speeds. It happens every time I begin to back up regardless if I turn the wheel or not.

Somethings that have already been done to the car:

-New Struts(KYBs)/Strut Mounts about 2 years ago
-New Tie-Rod Ends (and a right steering kunckle) a week ago
-Replaced Motor Mounts at home about 2 years ago
-A shop said the ball joints were fine, but past experience usually proves shops wrong.

Any ideas? Sway bar? A loose bolt in some random place in the front end?