Replacing lower ball joints on '99
 

I'm confused... the Haynes book indicates in multiple places that to replace the lower ball joints on '95/later, that I must replace the entire control arm... yet my local (Knechts) parts store indicates a replacement ball joint that must be pressed into place at a machine shop. So I checked two other auto parts store's online parts system; Autozone only showed the control arm, yet Napa also showed the separate ball joint being available for this year.

So which is it? Order the ball joints or the entire control arm?
It appears I have to remove the old control arms either way, but has anyone else here came across this contradiction?