It sounds like the Shift Interlock Solenoid.Be sure you have Brake Lights firstThe Brake Transmission Shift Interlock (BTSI) is designed to prevent shifting out of PARK without depressing the brake pedal. The BTSI Solenoid and the Park Lock Solenoid are energized when the Ignition Switch is in OFF, RUN, BULB TEST or START. When the Park Lock Solenoid is energized, the mechanical lock connected to this solenoid is pulled away from the shifter. The Stoplamp Switch receives ignition voltage in OFF, RUN, BULB TEST or START from the BTSI Fuse and is normally closed, providing voltage through circuit 1135 to the BTSI Solenoid, energizing the solenoid and mechanically locking the Transmission Shift Lever whenever it is in PARK. When the brake pedal is depressed, the Stoplamp Switch opens, removing voltage from circuit 1135 to the BTSI Solenoid. The BTSI Solenoid is deenergized and the mechanical lock connected to the BTSI Solenoid pulls back from the shifter, allowing shifting.
Shift Interlock Switch:
Shift Interlock Solenoid: