Something you might try. When you get up to 45 and it hasn't shifted into OD yet, a quick letup and speed up if your going to go faster it will immediatly shift into OD. it really saves on fuel. Did that when I went to Alaska in 2008, got 2 MPG more. Diesel was $7.00 a gallon then in Canada. I force shifted at 40 MPH. Was with my PSD.
