Friend had a 3/4 ton 4x4 IH Travelall back in the mid 70's. 7.50 Michelins truck tires maybe 33's and a 5 speed with both a granny low and overdrive. On trips west for elk it would push 20 mpg Had like 2.90 gears and 392 v8. Fun ride.

Elevation is math
Windage is Voodoo