So, I was doing pads and rotors and I noticed this on both sides. Looks like some kind of bushing? This car has a bunch of miles but is in really nice shape. I just don’t know what this is. I figured someone would be able to fill me in.

 

Bump stops.

Here's a recent thread with some further illustrations and discussions of the part:

https://ls1tech.com/forums/suspensio...tops-help.html