Balljoints

I have a 96 Maxima and last week I replaced the outter cv joint on the driver side but know it looks like I have to replace the lower balljoint which is ripe and don't know if it happens while I was installing the cv joint. I was told that I have to replace the entire control arm is this true. Also I'm looking at autozone & advance auto parts and they show pictures of a balljoint for you to replace. So do I replace the control arm as unit with the balljoint or just the balljoint itself which is about $30.00.

...So do I replace the control arm as unit with the balljoint or just the balljoint itself which is about $30.00.

Quick visual inspection should prove the joint bolt-on connection; see bigger pic at: http://www.cardomain.com/ride/748507/25

http://memimage.cardomain.com/member_images/4/web/748000-748999/748507_503.jpg