The car came with a tape deck and one four inch speaker in the dash to the left of the steering wheel.
I bought a couple of cheap Alpine 6x9s (Amazon link), traced and cut out a template for the space behind the rear seat in a flattened cardboard box, and then cut and screwed some plywood scraps together. Cut a couple of pieces of white metal gutter guard from Lowes to use as speaker grills and covered the whole deal in a saddle blanket.
I replaced the Sony cassette player in the dash with a cardboard blank…
…and installed a cheap Boss head unit (Amazon link) in the glove box.
The car came with a single 4″ Kicker speaker mounted in the dash to the left of the steering wheel. I left that in place and connected front left and right speaker wires to it.
Speaker wires were run under the carpet to the luggage compartment behind the back seat, connecting the speaker hutch.
I was expecting them to rattle, but they don’t actually sound too bad.