How do you shift a doug Nash 4 3 transmission?

To shift a Doug Nash 4+3 transmission, first engage the clutch and shift into first gear. For the overdrive function, while in fourth gear, pull the shift lever back to activate the overdrive, which provides a higher ratio for better fuel efficiency at highway speeds. Ensure to fully release the clutch before accelerating to smoothly transition between gears. Always consult the specific vehicle's manual for detailed instructions and recommendations.