As mentioned already you have a third party hitch and possibly wiring. Your hitch will have a dogleg around the muffler, either over or under it. The OEM is straight across.. but to clear the muffler it extends back farther from the original bumper thus Toyota provides a new plastic cover that replaces the original.
I recently installed a OEM and last weekend added my plug in. I wanted a dual / split type and one of the styles I liked was made by Ford. Ford wanted $103 for a new one... so in my infinite wisdom decided to go to the local scrap yard and get a used one for half the price. Except.. when I went to use it I found the clip for the wiring harness had been damaged and would not hold the wiring in place. By this time I had a bracket made and decided to "glue" the plug, replacing the clip part.. But.. the assembly ended up below the bumper where I did not like it.
Being as the wiring harness clip was toast.. and the assembly was too low for my taste.. I decided to make a modified version.. shorten it so that it would mount higher and solder all the wires to the pins.
Here is my plug with the excess cut off. If I had to do it again I would shorten it even more.. as it is it is tight against the trailer hitch.. 1/16 clearance would have been ideal
After soldering the wires to the pins I embedded the whole thing in an electronic grade RTV and then for good measure added a plastic pipe cap
The wires that come out of the plug are three from the Toyota wiring harness.. (lights only) the ground is pulled back and attached to the ground in the car. White 10 gauge ground to car; Blue 12 gauge electric brakes Black 12 gauge power and Red 12 gauge for possible future use.
I placed my bracket against the bumper, marked the outline, removed the bumper, cut the hole. Here is the bracket and bumper reinstalled.
Removed the bumper cover again, and mounted my plug.
And the final job.. I am really quite happy with the built in look.