I'll push my luck seeing how I'm new and ask if anyone has any experience with replacement interior panels. I've searched around some of the sites regarding replacement rear panels and it seems that there are two options. A company called "Designs of Steel"  makes plastic interior panels for the entire inside. My focus is for the rear left and right and tail gate. My Sammy is a soft top but i was planning on mounting speakers in the tailgate just like they do on the tin top. My speakers are shallow enough to fit but i have concerns over using the plastic covers verses say the diamond plate, has anyone played with this idea, I guess i could tack some sheet metal behind the plastic panels for support if need be. I like the idea of the palstic panels and have emailed the company with questions but they never got back to me. If i go with the stainless will it be sturdy enough to go without reinforcement?

You could just get some aluminum diamond plate and make your own.  There have been a couple of people that have built speaker boxes in the back of the Trackers, should be similar to what is needed on the SJ.

You could use a wood backing plate instead of sheet metal.

I got the plastic interior panels for my Sami, i got my through EBay and they were a hell of a lot cheaper than what other vendors were charging.  The plastic panels have no structure what so ever, i altered mine a bit so they wouldn't vibrate and make noise.  The little plastic plugs they send you to hold the panels in just dont do the job.  I ended up getting rid of  the plastic plugs and replacing them with some nutserts, button head screws, and some finish washers and it looks pretty good.

If you want make the tail gate house speakers i would make my own out of some sort of metal.  The tail gate is pretty darn simple.

Amilla