Ford Windstar Forum : “96 Windstar need to replace lower speedo cable and can't see tranny end. How muc...”

You will need to lift the vehicle and remove drivers tire.  The exhaust will be in the way, but you should not have to remove any pipes.  Follow the cable into the transmission.  Remove the Vehicle Speed Sensor ("Speedo Cable") with a 10mm socket.  This will have to be done by touch as you may not be able to see what you're doing.