I've got a 88 gmc s15 jimmy with the 4.3 and a 90 4l60 transmission. The truck has the speedo cable but the trans has the electronic speedo on it. I don't have it hook up yet because I need a two wire speedo to have one working again. There is nothing wrong with the stock speedo. It worked fine. I use my gps to keep up with mileage and speed too. But I'm getting a code 24 and the truck starts to run a little rough till I stop and restart it. Is there any ideas of what I can do?