U-haul sells a re-badged Drawtite hitch for the wagons. Simple three bolt install, takes 15 minutes. Around $90. The tailight converter is also available through them or online and requires a little patience and a torx driver to remove the rear hatch sill.

After scratching my head for awhile over where to pass the wires through from the converter to the exterior I fished them through the cabin vent just behind the driver's side rear tire. From there the harness snaked under the bumper cover to the hitch. I extended the power lead and ran it under the car to an in-line fuse at the battery. There are probably better ways to do it.

I pulled all this stuff off when I thought I'd sell the car but now we might keep it. Back on it goes.
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Erwin in Memphis, '88 745t 190,000 miles, '95 855t 92,000 miles