Ball joint problem? PLEASE READ!!!!

Okay, I've got a question. If the ball joints are worn out, or if the seals/grease fittings (I'm guessing that's what they're called) are busted, will I get some kind of noise from that problem? When I drive my car, I notice that car (1990 Mustang LX) when braking, accelerating from 0mph, or when going over noticable bumps, I hear a squeaking/grinding noise from the front suspension. I took the car to a mechanic and the guy there said that the ball joints need to be replaced. I thought it was the struts at first, and I replaced them, but I still have the same problem. He said that the ball joints can be replaced by themselves, but I thought the ball joints couldn't be replaced unless the control arms themselves are replaced as well. Could anyone help me out with understanding this problem a little more? Any help would be appreciated. Thanks.

Yes, the ball joints can be replaced by themselves. And Yes, they will squeak like crazy when they go bad. Mine went bad in my 96 GT and I actually thought it was the bushings making all the noise in the control arms. After I had both ball joints replaced, the car drives like a new one again! Spend the money and get it done right and be sure to get an alignment done after the work is done.