Need some input...Minnesota salt and winters broke the bolt on one of my stock rear end linkrods. Thinking this may happen to the other side I replaced both of them with Agency Power adjustable endlinks. (I also have a Swift rear sway bar) I have since noticed they too have started to corrode pretty badly and have lost their abilty to move on the ball joint and I now have a clunk. Close inspection today showed nothing loose anywhere just the stiff and slightly seized ball joints...I am not sure what the adjustabilty feature on these actually does? They are a quality looking part but I am wondering if their solid design (threaded collar etc.. no rubber bush) is what is causing the clunk? Sorry this is long...

 

bumper

 

I have the Perrin end links and haven't noticed any problems. They are similar to the AP ones you have. The adjustability lets you decied how long the end link is and how close the sway bar comes to the control arm. I have mine adjusted close to the stock length. I can move my ball joints by hand when the car is on the ground. I keep it in the middle so it can twist like left or right a little, Maybe you have it all the way to one side so when you hit a bump it can't go that way any more. Try readjusting them. I had to use one wrench on the end link itself to hold it steady. Try keeping it flush so its not all cockeyed. Its kinda tricky to tighten the lock nut without it slipping, then you have to start all over. Also you can try lubing the ball joints, try some white lithium grease.