eBay Score!
 

I was goofing off on eBay a few days ago and looking at a partial carpet set. It included the rear storage compartment and I noticed there was a wire with a plug sticking out of it. I took a chance and purchased it as it was less than $100 and sure enough there are speakers mounted in it! Pretty sure its not the factory kit but looks well done. Just need to run some wires to the radio or find the wiring harness made for it.http://986forum.com/forums/uploads02...1622985387.jpg

You could have two choices for wiring in rear speakers.

If you still have original radio, it has two sets of outputs on rear. One set is direct to speakers and there will be output for rear channels.

The second set of outputs goes to your amp … which you have if you have option 490, meaning speakers (woofers) in the doors. If you have this, you can go back to eBay and find a 6x40 amp from a 996 (911) cabrio to replace your 4x40 amp and connect your new rear speakers to that. This provides more power than the other option.

With either option, your fader will now work.