Don't worry about a Toyota OEM replacement, get the $30 aftermarket version. I've read on YT that the Toyota converter boxes are easy to fry when they get shorted out (as mine did, and so did yours probably ).
You can find the Hopkins brand boxes at Walmart, Autozone, or just about any auto parts place for ~$30. I tow an old beat up trailer and have shorted out the lights numerous times and haven't ruined the box yet
The worst part of the install getting to the old box. The box is under the plastic molding in the rear cargo area on the drivers side. Yeah like Ron said, use some care when removing the molding. I cut out the old box then I soldered all the wires in place and re-ran the trailer wire harness through the body. It took about 90 minutes. Some vehicles have "plug and play" harnesses that can be pluged into your factory harness without any spicing and soldering. My 2000 4Runner was not plug and play.