Instrument Cluster Issue

PS the AC Delco speedo repair centers set the mileage before they ship. That's why if the odometer is not readable you must send it in. They have other ways to get the mileage. They follow all federal laws about odometer readings. I handled thousands of these transactions at the GM and FCA dealer level. GM sold their medium duty division to Workhorse about 1996. Some GM dealers are also Workhorse dealers but not all. More than likely one gauge stopped working first and then more or all. See Youtube videos if only to help you understand the problem with these clusters, only the GM ID and number on the back will tell you for sure if it is one of the ones I reference. A high end scan tool will also pull the number for you. GM Tech 2, Snap On Solus for example.