That black piece? It's just for looks. No other use for it as far as I know.
I think I've changed my mind about the GT thing, and will instead order a ZR1 style LT1 emblem. Technically, it's suppose to be for a Camaro, but my Aveo is a 1LT (just the one is after the LT instead of before on the emblem). I can even get custom text, which will be AVEO5. And debadge all of the lettering on the back and transfer those onto the back of the clock like I wanted to with the GT emblem. The emblem is a little spendy, but pretty damn cool with tons of options.
ZR1 Styled LS1 LS2 LS3 Emblems
It'd look something like this: