Where is the overdrive switch on a 1989 Chevy Celebrity?

The 1989 Chevy Celebrity doesn't have a separate overdrive switch like some later cars. Overdrive is controlled by the transmission's selector lever. The position of the lever determines whether overdrive is engaged or not. Typically, "D" (Drive) engages overdrive, while a lower gear position (like "L" for low, or "2" or "1") will disengage it. Check your owner's manual for the specific details regarding your transmission's gear positions and their effect on overdrive.