I have a 07 Dually 4x4 with 6" lift and 22.5 alcoa and my shop today was going to do alignment and the passenger side ball joint no good I have had this setup sine May rougly 20000 miles.

 

The allignment shop jacks up the front axle until the wheel hangs in air. They then put a bar under the tire and lift it up and down, watching for movement in the lower ball joint. In my truck the movement (joint moving in and out of socket) was close to but less than around .100". It was the same, both before and after the replacement. 12k miles on the old joints, 8 miles on the new joints.

You can't feel any problem at the wheel. There may be some additional tire wear (cupping), but nothing radical with this degree of "loose". It was the same on mine. Passenger side looser than driver. That's also the side that needs some camber tweaking with an offset ball joint.