I have installed two of these digital dashes using the wiring diagrams found on this forum and had no problem using the stock fiero transmission speed signal with the cavalier dash. Keep in mind that there are two different toothed gears in the fiero transmission. I believe one is 29 teeth (red gear I think) and the other is 30 (if I remember correctly). The point being that the different gears could provide slightly different speeds from reality. I'm not sure which gear or transmission is used in the cavalier. The dash I installed in a friends fiero was off by I think 3 of 4 km /h at around 60km/h according to his GPS.
