93 Roadmaster wagon, how do you remove the rear speakers?

They have a plastic cover, what is the procedure to R&R.

I only have one working right rear speaker, all the others are dead?
I think that is odd, on my 1994 roadmaster wagon with premium sound, all the speakers work.

The removal of the cover is not all that hard, but you must be careful with the seat belt trim. The tangs that hold them on are extremely easy to break, and finding good ones is near impossible. You remove the panel with the storage bin, and you can then remove the cover. There are some black push retainers around the hole for the seat belt. Other than that, it has push clips to hold it on.

Be careful what speakers you replace the old ones with, there is a limited amount of space above the speaker, and the area for the magnet is limited as well. I assume that GM did not plan for any upgrades of the rear speakers.

If you drop one of the black fasteners, it will probably end up behind the vent in the rear door jam. The fasteners are available at your local parts store. Check for wheelhouse rust while you have it apart.

to get to them, I removed the rear panel with storage bin, or spare tire cover (depending on side) those are just snapped in along the top channel and floating in a channel on the bottom. Then like fred said, be careful with the seatbelt trim. under that are two black retainers to remove. Fold your middle seat down now if you haven't already. there is a pin/tab on the front side that gets hung up easily if the seat is up. the speaker cover snaps in the top channel just like the spare tire cover, and has two metal clips on the bottom. unlike the spare cover, the speaker cover does not extend to the bottom of the panel, just the top part. It will make sense when you go pulling on stuff.

When I had my rear speaker out, there was not much room above it, but looks are deceiving underneath. I measured 90mm depth without insulation. thats pretty deep.

I just took a pair of Pyle speakers from a wrecked wagon. They have a low top profile, and a large magnet on the back. The magnet just touched the wheelhouse. The top clearance is an issue if the speakers have an extended midrange/tweeter that is taller than the OEM units.