Where is the slot located for the obd2 located at on the 99 sts?

On the 1999 Cadillac STS, the OBD-II port is located beneath the dashboard, near the driver's side. Specifically, you can find it to the left of the steering column, often near the fuse box or just above the brake pedal. It may be necessary to adjust your position or use a flashlight to see it clearly.