The kit sort of uses a pulses per mile calibration. To calibrate it, you hit a button to start the calibration, drive a mile, and the system records the pulses when you tell it the mile is over. Or you can use a GPS sensor and don't have to deal with calibration.
See, I always was confused about where the speed sensor goes. Everywhere I looked online said it was on the driver side. So, I thought there may be 2 locations on the T56 Magnum, one for a mechanical assembly and one for an electronic version. I guess I should have looked at the passenger side. Here is the speed sensor connector the kit uses. I noticed it was a little different from the factory ones as this sensor requires a power, ground, and signal wire.
Intellitronix Speedometer Sending Units S9013