These GM DRAC modules have a range of 0.5 to 1.0 output ratio. If I keep the current 17 tooth vss reluctor wheel that's in my T56 trans, the module will need to output at a ratio of 0.28 for the 2.73, and 0.38 for the 3.73. These ratios are both lower than what these modules can do. I considered adding a frequency doubler to the input (effectively creating a 34 tooth input signal), but in the end I decided to change the reluctor wheel to a 40 tooth wheel. This will put me at 0.65'ish and 0.76'ish, well within the range of what these things can be calibrated for. Why did GM change to 17 tooth anyway for f car T56 only?? Even the GM aftermarket version of the T56 came with the 40 tooth wheel. Also note that I soldered a dip switch to one of them for easy calibration.