Well I took the rear housing to my friends machine shop and did a little work to it. I machined a flat spot on the case, drilled the proper sized hole, and threaded it for the factory 2006 4L80E 4x4 style rear speed sensor. I then took the original speedo cable piece and welded it up to seal the hole, didn't have a plug handy that had that thread pattern.
You can kind of see it here.
Far away, but these are the only three pics I could find that actually show it.
I did have more pics, but that computer died a horrible death, and I was only able to salvage fragments from the hard drive, which means I lost a lot of pics from back then. Like of the tone wheel I used with the spacers I made(just find one that fits the splined output shaft and make your own spacer sleeves to put it under the sensor). When you torque down the rear pinion, it will press against your spacers and keep the tone wheel from sliding back and forth in there.