Each of the gauges on these instrument clusters has a "stepper motor" behind it that moves the needle, and these motors are a common failure point to these trucks. When they go bad, they either fail to work at all, or stick in one position. A major aftermarket manufacturer (Dorman) offers rebuilt instrument clusters (with upgraded stepper motors) on an exchange basis. All you need is the VIN and mileage, then they program one and send it to your supplier, which you then exchange for your rebuildable core. They are reasonably priced, require limited down-time, and are fairly easy to install.
JS Auto Supply