I changed the rear end gears from 3.42 to 4.10 in my 88 C1500. I was able to calibrate my speedometer display easily with my Dakota Digital dash. My problem is, while data logging in TunerPro RT the speedometer there still thinks I have 3.42 gears which throws off the parameters for TCC etc. or will I have to convert all MPH related parameters manually?

Does anyone know of a "hack" or easy way to calibrate the speed in the ECM? I really don't want to have to go through the hassle and expense of buying a signal interface and rewiring the input.