The first spin around the block revealed that the speedometer wasn't working. At the time, there were several reasons why this could be.

1) Electrical problem (wires not connected in correct order, blown fuse, bad sensor, etc)
2) The sensor was providing the wrong type of signal
3) The speedo gear housing wasn't clocked properly

I started with the first item on the list. I checked the wiring and verified that the ground was good and the sensor was getting a full 12v.

Scratching my head, I decide to check the third item on the list. I pulled the speedo sensor/gear and reinstalled it while making sure the gears were meshing properly. Another spin around the block confirmed that the speedo still wasn't working.

At this point, I decided that the second item on the list was the culprit. This turned out to be the case. What little information I could find online suggested that the Jeep sensor was an eight pulse per rotation, square wave sensor. From what I could tell with an analog multimeter this was not the case. It appeared to be a sin wave sensor.

This is where I got the bright idea to check the stock Montero pulse sensor. It was clearly a four pulse per rotation with a square wave.

After reviewing all the speedometer gears, stems, and housings that I had, I realized that the threads on the Montero pulse generator were very similar to the threads on a stem I had from a cable driven NP231 speedo. I carefully threaded the two together and realized it could work! Unfortunately I needed an adapter key to mate the two shafts together. After measuring a stem from another part I had, I knew that I needed a double male .104 square adapter key. Most of you have probably read how I found that part.

Now that I had a complete sensor assembly, I installed it in the t-case and went for another test drive.