73 duster front end popping when turning left or right.

Not much to go on there. Does it only do it when turning? Or with suspension travel too? Does it do it sitting in your driveway turning the wheels, or only when you're driving and turning left and right also has a body roll component? Are there any other symptoms, like extra play in the steering, or just the noise?

If it only does it when turning, I really doubt the shock mount bushings are the issue. They'd be making noise every time the suspension moved up and down too.

What did you do to check the tie rod ends and ball joints?

Could be a lot of things, everything from a loose joint all the way up to cracked welds on the steering box mount.