1994 Prado 3.0 1kz-te engine, manual transmission with 200k km. On Okinawa, max speed is 80kph so 4th gear has been my usual choice. Power is smooth and I cruise at 80kph in 4th at 2,400 RPM. I need to hit 90-100kph before 5th gear is even usable. At 80kph, 5th gear bogs at 2000 RPM. Is this...