Do all firebird have the plug for the CD changer?

i was reading about the 12 or 10 Cd changer and it said the plug was in the left rear by the quarter panel.....i was looking i didnt see anything? do all firebirds have that port???

If your car didn't come with it I don't think the wiring is installed

What year bird are we talking about here. I have had several third gens, and as far as i know none of them had it.
Jake