Be very careful when replacing ball joints on a P-30 chassis. Some P-30 chassis have rear drum brakes and some have rear disc brakes. Drum brakes are on the smaller lighter P-30 chassis. I had two front end ball joint failures because a local shop installed the wrong ones twice. I have disc brakes and they installed the undersized ball joints for drum brakes. And yes they will only last a year or less if undersized ball joints are installed. If you hear a clunking sound the tapered section of the joint is probably working back and forth in the hole work hardening the shaft and elongating the hole until you are going around a corner at 60 mph and failure occurs.