So I got a '96 f140, 4.9, man. I put the key In the on position I got Ignition lights buzzer cab light when I go to star I loose ignition and panel lights keep cab light changd sili batt chkd alt am I

When the key is turned to the start position it is normal to loose electrical power to certain accessories because all the voltage and amperage is being diverted to the starter to engage the engine. Does the engine start or try to start when you turn the key? Is that the problem? If you have a dead key when turned to start it could be a low battery, but you said you checked that. It could also be the ignition switch inside the steering column, not the key lock into which you insert the key. A multi-meter and wiring diagram is going to be required. With someone turning the key to the start position I would first check the solenoid relay mounted on the fender well near the battery making sure it is working and sending voltage to the starter.