How do you change the rear speakers in a 1992 Nissan maxima?
Open the trunk, release all of the white plastic clips holding down the rear dash. Pull up on the rear seat to remove it. Remove the rear dash and unscrew speakers from the top. Factory connections will need to be cut and wire ends will need to be put on them. In most cases a stock clarion amplifier will run the stock speakers. This should not effect the aftermarket speakers.
Try to use the Nissan speaker adapters plugs so you don't need to cut wires and mess up the electric system, you can get those from eBay or amazon.