Just purchased all the ball joints (upper and lower) for my 05/XK8 Conv. from Coventry West on 6/9 (I believe- may be off a day or two). Anyway when replacing the Upper Shock Mounts, I found out all Ball Joints were fine. Paid 45 bucks each-- plus tax, so have all for sale if anyone is interested. Will sell them all for 40 bucks each- plus free shipping. Still in original packing. Would return them, but their restocking charges are too steep.
Contact me via email.

Thanks

Chuck

 

By the time you need them you probably won't be able to buy them so inexpensively - you may consider just hanging on to them.