Just did this last night
Kevin,
Well, the speaker is set in the black plastic unit under the grill. Once the grill is removed, the black plastic unit with speaker lifts out. It comes out if you lift up, and pull toward yourself as you are sitting in the back seat.
You will also need to unplug the connector. Once you have the black plastic unit with speaker out, you need to remove the defective speaker from the plastic part. It was glued in on my vehicle and took a fair about of prying from two or three points. If eventually gave up and came out.
I bought a set of replacement speakers from Car Toys. They are German made MB Quart DKD 113 130 mm/5.25 inch speakers. I think they were 4 ohms, a little lower rated than the originals - not sure.
I drilled holes in the plastic and mounted these new speakers in place. I also had to take the old wire off of the old speakers and add connectors to slid on to the tangs. Right lead seems to be positive. Sound is better than original at this point.
Cost of speakers $139 plus tax. I installed myself.
Hope this helps.