Hi all, gutting the interior of 87 single cab 2wd. I took a few pics so I could ask a few questions about stuff. With this one the long black thing used to go behind the seats, up against the rear wall of the cab. Is it needed? What's it really for? I know that you can buy some of those metal brackets that hold the rear cab speakers, that hold bigger speakers, but what keeps you from just taking your cutting wheel (or whatever) and making the holes bigger so that the fit a larger size speaker? Why would you need to buy new ones?