chassis ground wire on harness

I am installing a new stereo in my car. Someone else removed this stereo from my old car and I am putting it into my s-10. On the wiring coming from my cd player there is a black wire with a horseshoe shaped screw fastner. The black wire from the the harness says chassis ground but the black wire on my old harness was not used.
Can anybody clear this up for me...thanks in advance

You need a ground.You choose which way you want to do it.Either splice it into your aftermarket wire harness or find some bare metal and screw the horseshoe connector to the metal.I would use the aftermarket harness myself.

I really don't recomend this but I installed a stereo once that I must have missed the ground wire on. It worked just fine until I removed the antena before I found I had missed it.