You can buy the slider bracket from Toyota part number 69806-35010. Its very common for the plastic to break off..
I just replaced the tracks on one of my 4 runner as my driver side bracket rusted off. If your not in the rust belt. Most likely you will be able to reuse the bolts. If not your going to need new bolts for for your bracket. The nuts for the rear door (hatch)are built into the glass plastic bracket that attaches to the glass. If they are rusty get ready to have to put new bolts and replacement nuts in to attach the glass to the windows regulator. They are 10mm heads. So 6mm diameter threads. Probably need threads longer then 12mm as well closer to 14 or 16mm of threads so a nut can smash into the plastic. I used flange nuts when i fixed my rear window