I just have to mention all the other maintenance that needed doing at 100K, especially the transfer case every 50K. (I know I"m a broken record about this, but not everybody reads all my reminder posts...
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I assume it's your UCA bushings that make you need a new one. I'd do both at the same time, since they are only like $50 for aftermarket ones. You need to bend or cut fender sheet metal out of the way when you remove the bolts because the GM suspension designers weren't talking to the sheet metal designers in terms of "can anybody change this out inthe future after the assembly line plops the body onto the frame?"
The other items are "change them if they're loose". Ball joints are testable using a process that's well documented on Youtube and other auto maintenance sites. I don't think we have a comprehensive how-to article here. In general, if you're not slinging it about offroad, your LCAs are probably good. Most folks find looseness and noise coming out of the anti-sway bar end links, or inner or outer tie rod ends, or their hub bearings, before they need control arm renewal.
If you've had it aligned, the alignment tech would check all the parts for looseness, in hopes you'll pay that shop to replace the parts. What's your alignment situation?