Control arm interchange?

My friend has some nasty balljoints on an '89 and wants my '00 front control arms. I plan to put on a D&D set this pay depending on whether this will work. Do I need the K-member to put them on my car, or can I wait on that for a month or so? Better yet, will my CA's work for his car?

I'd really like to save this guy some money if I can. Whatever I can save him might find its way into his 200K miles old GT.