[Billett]

Final ratio's will always be 1:1 unless you have overdrive. I drive slow as well because I drive the highway so much. I keep it to around 60mph the whole drive because the truck just feels like it isn't trying nearly as hard as when I get it to 70 or so, if that makes sense. If I drive it like that I get around 12 mpg, but that isn't accurate because my speedo is off, by a factor of 1.2, so when it says I'm doing 50 I'm actually going 60. Because of that I actually get more, just not sure how much.

Just for more info, I have a '68 with a stock 350, NP435, LWB fleetside, 3.73 open rear, and 275/60/15 tires.