Is that the ball joint I can hear..?

[SDL69]

Hi, having had my '71 van lowered last Summer, (adjusters at the front and brought down one spline at the rear) one of the drivers front side front ball joints decided to play up and start knocking. Having had it replaced one of the ball joints on the passenger side (front) decided to follow suit. Now I have a knocking sound from the back (near side) and am wondering if it is the ball joint, it kind of only happens when I turn left and the momentum of the knocking changes with the speed I am travelling...........It's driving me potty cos I have had two mechanics look at it and both say they cannot find any fault.

Q. Do ball joints usually start knocking after have the van lowered...?

 

[RICH-I-AM]

Sounds lile a driveshaft joint to me although usualy the noise comes from the joint bearing most weight ie.. when turning left the weight is on the right side n when your turning right the noise is on the left.
Anyone had a drum off?