Can not turn off overdrive on 1999 e 350 7.3?

To turn off overdrive on a 1999 E-350 with a 7.3L engine, locate the overdrive button on the gear shift or dashboard. Press the button, which typically has an "O/D" label, to deactivate overdrive mode; the indicator light on the dashboard should illuminate. If this doesn't work, check the vehicle’s Transmission Fluid level and condition, as low or dirty fluid can affect shifting. If problems persist, consider consulting a mechanic for further diagnosis.