I put a taller gear in my 37 and the gas mileage got worse,I also had a weak fuel pump and was in the gas more then usual to keep it going which could of been opening the power valve causing the drop in gas mileage but I have not driven it too far since the pump replacememnt to see if mileage improved. I got 2.79 gears in it and its a totally different truck and its quick off the line but I might be straining it a little. Jeff
