I want to replace my dash speaker, I've taken the ashtray and ashtray bracket out, the 2 top screws off the plastic trim that are located on top of the radio, and the bolt that holds the radio on the back to tha "L" shaped bracket, the radio is more or less loose, but it seems to be anchored at the bottom somehow, I don't want to yank it out in fear of breaking something. Is there a fastener that I have maybe missed? Also it has a blue wire with a connector coming out from it. Im pretty sure this car didn't have the rear speaker option, can I still hook one up from that wire? Here's some pics of the unit and the wire.