Front suspension clicking noise

[quentin hill]

On my 72 I have a really annoying popping then clicking noise and it is in the front left suspension area. Has anyone ever had this problem? At some point in the trucks life someone replaced the upper A arm. Not sure if the truck was in an accident or what.
Anytime I take a hard right there is a POP and then a click click click noise. I have replaced the bearings and still no change. I have made sure all the joints are full of grease still not change.
I used a floor jack with the truck raised to simulate the movement of the A arm and I can feel it POPPING but cannot pin point the location. I really do not want to tear it apart but may not have a choice.
One other observation is that only on the left side, the rotor has a groove in it, like it was one someone found and just put it on the truck but the groove is machined in about mid way on the rotor. Could this cause the brake shoes to click?