Took out my back seat to try and fix defroster. Couldn't figure out how to remove trim near windows without breaking it so I gave up. When I put the back of the seat back on the two 8mm screws on either side went in fine. The center screw had nothing to screw to, there is just a kind of too big rectangular hole. Was there some kind of plastic thing there that served as the anchoring point for the screw or did some kind of captive nut drop off in back? Not a biggie since the seats not going anywhere, just aggravating. Thanks.

There's a metal "clip" that goes there. The clip allows the threads of the screw to go in. It probably fell out and is under the seat somewhere!

Thanks speedy300Dturbo ('cept when it's cold!). Found the damn thing, all it had done was shift around, took everything apart again :-(