i dunno. Mine does a high pitch squeak like you describe and even does it while there is no back seat (like right now)

 

i took yet another hour out of my life tonight looking at the damn jeep. out of 3 bolts underneath the rear seat fastening it to the floor, 2 were not even threaded (they were just sitting in the hole)...so i attached/tightened them thinking i had just fixed it...NOPE. still squeaks.

then i think i finally found the problem (ALTHOUGH I WAS STILL NOT ABLE TO FIX IT). the problem is the rear portion of the bench seat that has 2 seats. the squeak can be reproduced by me by pulling on the latch on the top of the seat to release it forward to flatten, and then moving the seat back and forth JUST as you feel it beginning to catch to begin the re-lock in the upright position. back and forth it makes the squeak.

it is also produced by clenching my fist and hitting the centre area of the seat where the back of your knees rest while sitting down. I tried oiling the hinges etc inside the seat, and the headrest too, and i tried pulling up the fabric on the back of the seat, but i cant get into it too far. the squeak is STILL there.

any ideas? or just make another (4th) app't for this completely annoying problem that is consuming me?

 

Is there such a 'latch'? Where would I look for that? I was looking at the rear portion of it trying to figure out HOW it came to lock back into its upright position, but didn't see how....