2007 F250 diesel tachometer issue

Hello, it seems like a cluster problem. It can be verified by using a Ford IDS diagnostic tool (or equivalent) to perform body module testing on the IC - instrument cluster module. You can monitor the tachometer signal to then cluster. If the signal is accurate to the actual engine operation and the tachometer reading is off by 2500 RPM, then the cluster must be replaced. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops