Dreaded clunk when turning

66 dart, sedan, L6 with the stock suspension and axle and differential. 7.25
Everything been going fine, until yesterday , whenever I turn to the Left, there is a loud clunk in the right rear, and feels like a little jerk as well.
It is pretty loud. Doesn't happen when driving straight, no grinding. Only on the turn.
I bounced the rear end up and down, but makes no sound.
The shocks are only a few years old. How do i diagnose it? Thanks guys.