Take the cable off from the black terminal of the battery. Remove the center bezel panel from the dash. Take out the screws, pull the radio from its dash slot, and disconnect the antenna and electrical wires while you do this. Installation is the reverse of removal. To replace the speaker in each door, take out the matching door trim panel. Unbolt the speaker with the screws under it, disconnect the socket, and carefully pull the speaker out, reversing these steps to put it in place. Remove the rear quarter panel trim from the Xterra/Pathfinder, unhook the electrical connector, unscrew the speaker mounting bolts, then remove the speaker. Installation goes the opposite way of removal.