1990 toyota corolla

Pull on the tabs on each side of the seat then lift the bottom seat cushion and pull it out.  Then there's two 12mm bolts to remove, one on each side, and then you can lift the seatback up and remove it.

there's 3 plastic panel push-in thingies on the front edge of the rear deck which you need to remove, in order to remove that entire plastic piece.  Then there's two bolts on the 3rd brake light that need to be removed, and then the entire brake light assembly itself needs to be unplugged and removed.

Now just pull straight out on the top deck and it should come right out.  Then for each speaker/adapter assembly there's 4 phillips screws to remove, and usually the adapter is not used when you put in aftermarket speakers.  You may have to drill your own holes for screws to secure the aftermarket speakers.

Thanks, Ethan that doesnt sound too hard, have you ever done speakers in a corolla , and what size aftermarket do you think would work best? also I looked at the dash speakers do I have to pull the whole dash to get at those ones too?

Just trying to get my wife's commuter car to sound good. I did the entire install on my 98 dodge stratus, that was much easier for some reason.