Take the speedo output wire from the PCM and hook it to the speedo wire going to the instrument panel. That should get the speedo working. I'm not sure how you handle the anti-lock brakes on that year model. If you have the 96 PCM still installed you should be able to connect the 96 speedo wire leads to the 03 speedo wire leads going to the transmission to keep that stuff working. I think I remember someone saying you have to cross-match the colors, green to purple and visa-versa.