Replacing Speakers

Overview

In my 1989 560 SEC the speakers installed by the previous owner were shot and poorly installed.  I decided the replace all the speakers with:
  Rear: 2-Infinity 6.5" 2-way (6521)
  Doors: 2-Infinity 6.5" 2-way (6521)
  Front: 2-Infinity 3.5" 2 way (3052CF)
All were available from Circuit City.

There is a fitment problem with replacing the factory speakers with easily available generic speakers.  Especially the 2-way speakers which tend to be deeper and don't fit in the space provided.  I wanted to replace the speakers with the largest speakers I could find that would be able to be installed with no visible modifications to the cabin interior.

Install - Rear Speakers

The new 6.5" 2-way speakers would not in the rear parcel shelf openings, because the speak magnets hit the rear strut tower.  I took a 1-gallon metal paint can and cut the bottom off in a wedge shape, with one side of the can at 1-3/4" high and the opposite side cut to the lip of the can.  Leave about a 1/2" of the can which will be cut into 3/4' tabs around the perimeter of the can. Most of these tabs will be folded in and a few folded out to be used as screw mounting tabs when securing the assembly to the parcel shelf.
Start by cutting a hole out of the bottom of the can big enough so the speaker fits flush and leaving enough of the can bottom to attach the supplied speaker mounting ring.
I then painted the speaker mounts black.  I made 2 gaskets from a sheet of foam rubber and installed them between the mounting ring and the can and between the can and the parcel shelf (Fig-2).  
When installing the mounting assembly, position the lowest side towards the front inner corners of  the parcel shelf (Fig-3).  This points the speakers towards the center of the cabin and permits maximum clearance between the speaker and speaker cover (Fig-1).

Fig-1

Fig-2

Fig-3

Install - Door Speakers

I replaced the factory 5.5" mid-range speaker with the 6.5" 2-way speaker with very little trouble.  They fit almost perfectly in the factory speaker boxes mounted in the doors.  The only thing I had to do was dremel out little notches from the plastic box so that the speaker 4 screw mount ears would fit.  The screw holes all lined up perfectly.  I wired up the speaker as the original speaker was wired using the transformer.

Install  - Front Dash Speakers

The 3.5" 2-way speaker fit the in the open with plenty of room, but the screw holes can up short.  I fashioned a pair of brackets for each speaker to secure the speaker to the dash.  Mounting straps cut to the required length would work just fine.

Disclaimer

This procedure was done on my 1989 560 SEC and I can't say if this procedure will apply to other years and/or models.  This procedure worked for me and anyone else should use this writeup only as a reference.