1998 f250 4.6 4x4. In park the starter engages with key on . Ounce running the starter is still engaged in park and neuntral. No engagment in the drive gears. changed the ingition switch and neutral saftey switch on the trans. when key is off insturment cluster is still on. any help

 

When you say "ignition switch", do you mean the key and tumbler assembly, or the switch with the wire harness below the columm?

 

Something else I thought of. If the bottom solinoid is shorted, as soon as you turn the key to the run position it will crank and continue to crank even after the motor starts. Are you sure the dash light switch is not engaged? I don't get how the two are related....someone will be along though that knows more ....

 

The starter relay contacts are likely burnt togather once it's powered up.
That's the only way the starter would get power to run unless there is a short to battery in the pull up circuit to the relay winding.
Good luck.