Lower control arms
 

I have a ball joint that needs replaced on my S5, however, the ball joint is non replaceable on the S5.

Is the only difference between the S4 and S5 lower control arms the replaceable ball joint, or are other things different. The reason I ask is I need to replace it, but I'm not willing to spend the $600 for a new one from Mazda.

Sway bar end links are different too. Including the mounting points on the arm.

I would not bother with the s5 control arm components and get s4 control arms instead. It has replaceable ball joints.