Where is the overdrive switch located on a 1998 Ford Windstar?

The 1998 Ford Windstar doesn't have a separate overdrive *switch*. Overdrive is controlled via the transmission's selector, typically found on the center console. The selector will have positions like Park (P), Reverse (R), Neutral (N), Drive (D), and often a position like 1 or 2 (which disables overdrive). To disable overdrive, you would usually select the 1 or 2 position. Check your owner's manual for the exact position to use to disengage overdrive.