I have a 89 gmc sonoma 2.8 there was a converter box between speedo cable and trans. It broke and dash is now off by 15 mph. What is the part called and were do I find one
It is called a speedometer transducer box, if you can't get one from the dealer try looking for a good used one with the same ratio or take yours to a speedo repair center and they may be able to rebuild yours. It won't be cheap. i worked at a speedo calabration shop and we made these up for hotrodders at that time it ran 120 bucks for the box and gears and another 70 for labor.
Search GMC Sonoma Questions
GMC Sonoma Experts