Related to what Blake442 had mentioned, I believe you can get a replacement for the factory single speaker from Custom Autosound, which already has the plate with 2 3" speakers mounted and ready to go. Check out JCWhitney, that's the last place I saw it.
My dad and I mounted 6.5" coax speakers in the cubbys in the back of his '81 'Bu using some mdf cut to fit, so 6x9's should fit but check the depth. As for the kick panels, the e-brake pedal interfered with what we wanted, but luckily his wagon had the two 3.5" speakers from the factory.
Good luck!
Aaron
My dad and I mounted 6.5" coax speakers in the cubbys in the back of his '81 'Bu using some mdf cut to fit, so 6x9's should fit but check the depth. As for the kick panels, the e-brake pedal interfered with what we wanted, but luckily his wagon had the two 3.5" speakers from the factory.
Good luck!
Aaron
