What about if it doe not grind then what

Some push in some are the arm some bolt in . If your new one has bolts and looks correct then the old one is riveted in if this is the case you will need to grind the rivit and drift it out of the arm to release the ball joint. If thus is the case personally id go and buy a arm just for the ease of it

just the ball joint
check -if the ball joint is riveted into the lower control arm, it will be necessary to grind the rivet heads then punch out the rivets
replacement ball joints should come with the bolts needed to replace the rivets
some lower control arms have the ball joints pressed in so it is necessary to press out the old ball joint then press in the new unit

Could be your has been replaced before.I do a lot of different vehicles, so bear with me. All joints are basically pressed into the spindle with the nut. Hammer on the spindle at the ball joint to get them to release. Some joints are bolted on, some are riveted on (grind, heat and beat them out) to the lower control arm some are pressed in. If yours is bolted on the lower control arm, remove the bolts. Knock the ball joint out of the control, replace it. Consider yourself lucky.

Lower ball joints attach the lower "A"-arm to the bottom of the strut assembly or steering knuckle. Original ball-joints are usually rivited on and require drilling or grinding to remove. The vehicle must be raised and supported when doing this. Seperating the balljoint from the knuckle requires a splitter fork and a lot of pounding. Not something I would recommend for a novice to attempt.

sorry but impala ball joints are not pressed in they are secured by rivets

Beat on the spindle that holds lower control to the lower spindle while prying the lower control arm down this will loosen the lower ball joint spindle. If there is a lock bolt take it out. Grind the rivets off in the lower ball joint. The new one comes with bolts to replace it (not rivets)

Although you never said what model, 2 or 4 wheel drive and the engine size, I looked around and found this.
Both 2 & 4 wheel drive take the same ball joint &/or upper control arm. You can opt to do what ever is money wise or easier for you. Auto-zone carries both. You can press a new one in for about 30 bucks or replace the arm with the ball joint for 104. Auto-zone will lend you the press for no charge if you buy the part there. And as far as indexing, yes always. Although anytime front end components are changed a front wheel alignment should be done. The bushing bolts are your Camber adjustments.
http://www.autozone.com/autozone/parts/1999-Chevrolet-Silverado-1500-4WD/Ball-Joint-Upper/_/N-jdwjeZ8oxkv

You'll need to seperate the control arm from the wheel hub. If the ball joints are installed with rivots, you'll need to grind off the heads and knock them out with a punch. The new ball joints should have bolts and nuts to reinstall the new ball joints. Don't forget to grease the new ones, they come with very little grease installed.

check your cv joint attached to the knuckle arm it must have been broken...

They are riveted into the lower control arm. You can chisel them out OR...if u have air tools...u can grind the rivets off, them punch them thru the bottom of the lower control arm. Make sure you place GOOD, STRONG jackstands under the control arm. I believe that is a torsion bar suspension so be very careful. You'll also need to pop the upper ball joint out of the spindle to change the lower ball joint. Good luck.

Chris